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ROPER'S 
Practical Hand -Books 

For Engineers and Firemen* 



NEW REVISED AND ENLARGED EDITION. 

HANDY-BOOK FOR STEAM ENGINEERS 

AND ELECTRICIANS. 

PRICE, $3.50. 

PRICE. 

Roper's Catechism for Steam Engineers and Electric- 
ians, $2.00 

Roper's Questions and Answers for Steam Engineers 

and Electricians, 2.00 

Roper's Hand-Book of Land and Marine Engines, • 3.50 

Roper's Care and Management of the Steam Boiler, 2.00 

Roper's Use and Abuse of the Steam Boiler, • • • • 2.00 

Roper's Young Engineers' Own Book, 2.50 

Roper's Hand-Book of the Locomotive, 2.50 

Roper's Instructions and Suggestions for Engineers 

and Firemen, 2.00 

Roper's Hand-Book of Modern Steam Fire Engines, • 3.50 



DAVID MCKAY, Publisher, 

1022 Market Street, Philadelphia, Pa. 



ROPERS 

QUESTIONS AND ANSWERS 

FOR 

STATIONARY AND MARINE 
ENGINEERS 

AND 

ELECTRICIANS 



WITH A CHAPTER ON 



WHAT TO DO IN CASE OF ACCIDENTS 

JR\th (gtUtion, llctmtten and 6r*athj 
(ftnlarfled by 

EDWIN R. KELLER, M.E. 

AND 

CLAYTOX \V. PIKE. B.S. 
Ex-President of the Electrical Section of the Franklin Institute 



PHILADELPHIA 

DAVID McKAY, Publisher, 

1022 Market Street 



42274' 

Library of Conqrese 
TWO COWS RfCf«V€0 

SEP 1 1900 

Copyright antry 

9lAm /3, l<f&4 

SECOND COPY. 
O'MHH DIVISION. 

SEP 6 19d0 






Entered, according to Act of Congress, in the year 1880, by 

STEPHEN ROPER, 
In the Office of the Librarian of Congress, at Washington. 



Copyright by DAVID McKAY, 1897. 



Copyright by DAVID McKAY, 1900. 



£4289 






d- 5 



bO 



PREFACE TO THE REVISED EDITION. 



Like the early editions of the " Questions and 
Answers for Engineers, ' ' the present revision is in- 
tended for stationary engineers as well as those in 
the Mercantile Marine. At the time when this 
book was first written there were no published 
requirements for either of these two classes of ser- 
vice, and even at the present time it would 
be difficult to say just what should be the 
qualifications of stationary engineers. Some of the 
States have attempted to formulate the require- 
ments, but there has been nothing evolved as yet 
which specifically states them. It would, in fact, 
be a difficult matter to comprise in one formula 
all branches of this service, but it is to be hoped that 
something in this direction will be accomplished 
in the near future by the co-operation of the 
various States and subsequent legislation. 

For Marine Engineers the only requirements 
established by law are contained in the Regulations 
v 



VI PREFACE TO THE REVISED EDITION. 

of the Steamboat Inspection Service of the Treas- 
ury Department. These, however, are stated in 
such a general way as to be of little service to 
an applicant in fitting himself for this service. 
As the requirements of the Mercantile Marine are 
very fully stated in the Frye Bill, introduced at 
"Washington in January, 1892, the authors have 
deemed it advisable to make it a basis for the 
questions even though it did not become a 
law. 

This bill is the result of certain recommenda- 
tions from theU. S. delegates to the International 
Marine Conference and is based largely on the re- 
quirements in other countries. It contains not 
only rules governing the inspection of steamboats, 
but it states in a specific way just what shall be 
the qualifications of engineers. According to this 
bill, those in charge of the machinery on steam- 
boats are divided into Chief Engineers and First. 
Second and Third Assistants. Such portions 
as have a direct bearing on the qualifications of 
these are here printed in full, but the subsequent 
questions and answers are confined to the first, 
second and third assistants' requirements. The 



PREFACE TO THE REVISED EDITION. Yll 

authors have purposely omitted a detailed con- 
sideration of the requirements for chief engineer, 
not only because they are beyond the scope of 
Roper' s series of books for practical engineers, but 
also because the chief engineer's qualifications are 
largely covered by the requirements of the assist- 
ants, excepting in so far as they relate to electrical 
matters. 

A series of electrical questions and answers has 
been added for Dynamo Tenders and Wiremen. 
As the greater part of their work is confined to 
low pressure direct currents, it has been consid- 
ered advisable to confine these questions to that 
class of work. 

Of course, it would be impossible in a book of 
this kind to cover all of the questions that might 
confront an applicant on examination, and the 
authors have confined themselves to the more im- 
portant subjects and selected such questions as in 
their judgment would on the one hand give a fair 
test of the knowledge of the applicant and, on 
the other, a well prepared engineer should be 
capable of answering. 

The authors desire to express their obligations 



Vlll PREFACE TO THE REVISED EDITION. 

to the following gentlemen who have so kindly 
assisted them in the preparation of various parts 
of the book. To Mr. Samuel B. Locke, for prac- 
tical questions for Firemen and Stationary Engi- 
neers ; to Mr. W. H. Thorne, for questions for 
Marine Engineers; to Augustus Koenig, M. D., 
for the chapter on ' ' What to do in Case of Acci- 
dents." 

Edwin R. Keller. 

Clayton W. Pike. 
Philadelphia, August, 1900. 



CONTENTS. 



Questions foe Fieemen. page 

Boilers, Different Classes of, 1 

Care and Management of, 10 

Formation of Scale in, 18 

Foaming in, ... 20 

Safety Valves, 21 

Gauges, 22 

Pumps, 23 

Injectors, 25 

Feed-water Heaters, 27 

Grates, . , 28 

Stokers, . . . .* 30 

Damper Eegulators, 33 

Questions foe Stationary Engineees. 

Horse-power of Boilers, 35 

Evaporative Efficiency of Boilers, , 37 

Heating Surface of Boilers, ... 38 

Construction of Boilers, 41 

Boiler Setting, 45 

Scale, 46 

Foaming, 48 

Safety Valves, 49 

Gauges, 51 

ix 



X CONTENTS. 

PAGE 

Pumps, 54 

Injectors, 57 

Feed water Heaters, 59 

Boiler Flues, 62 

Grates, 63 

Stokers, 65 

Chimneys, . 06 

Steam Traps, 68 

Boiler Eepairs, 71 

Steam Engines, Power of, 72 

Types of, 78 

Valve Gears for, 85 

Governors, 97 

Foundations for, 98 

Care and Management of, 99 

The Steam Engine Indicator, 105 

Condensers, 10S 

Less Practical Questions, 109 

Steam Heating, 123 



Questions for Marine Engineers. 

Rules of Supervising Steam Inspectors, 132 

The Frye Bill, 140 

Classification of Engineers, 144 

Qualifications of 3d Assistant Engineers, . . laO 

" " 2d " " . . 151 

" " 1st " " .' . 152 

" " Chief Engineers, 153 

Questions for 3d Assistant Engineers, 159 

11 " 2d " " 172 

" " 1st " " 192 

Requirements for the Revenue Marine, 223 



CONTENTS. XI 

ELECTPJCAL QUESTIONS. 
Questions foe Dynamo Tenders. 

PAGE 

The Dynamo and its Parts, 227 

Electrical Distribution, 239 

Switchboard and Apparatus, 240 

Dynamos in Multiple, 247 

Rheostats, 249 

Instruments, 250 

Motors, 252 

Wiring Systems, 256 

Questions for Electricians oe Wiremen. 

Systems of Distribution, 258 

Determination of Sizes of Wire, 260 

Varieties of Wiring, 261 

Arc Lamps, 269 

Electric Bells and Annunciators, 273 

Watchmen's Clock Systems, 276 

Batteries, 278 

Telephones, 282 

Electeical Units, Properties and Measurement. 

Electric Pressure, 288 

Current, 289 

Eesistance, . 290 

Ohm's Law, 293 

Measurement, 296 



QUESTIONS AND ANSWERS 

FOR 

STEAM ENGINEERS 

AND 

ELECTRICIANS. 



QUESTIONS FOR FIREMEN. 

Q. How would you classify steam boilers ? 

A. Into cylindrical, flue, fire tubular, and water 
tubular. 

Q. What advantages does the plain cylinder 
boiler possess over other types ? 

A. It is simple, inexpensive, easy to clean and 
repair. 

Q. Are plain cylinder boilers much used at the 
present time ? 

A. No; they have disappeared almost entirely, 
mainly on account of their inefficiency. They 
are found occasionally in localities where the cost 
of fuel is very low. 

Q. Name the principal varieties of flue boilers 
and briefly describe their characteristics. 
1 1 



A QUESTIONS AND ANSWERS FOR 

A. The Cornish, Lancashire, and Galloway 
boilers are the principal varieties of flue boilers. 
In the Cornish type an internal cylindrical flue 
extends the whole length of the boiler, and the 
furnace is usually contained in the tlue. The 
Lancashire boiler has two internal flues with a 
furnace in each, the two flues uniting into one 
behind the bridge wall. The Galloway is similar 
to the Lancashire, but has a number of conical 
tubes, called Galloway tubes, inside and across 
the flues, through which the water circulates. 
The furnaces are either within the flues or ex- 
ternal. 

Q. What are the relative advantages and dis- 
advantages of the above-named boilers? 

A. The Cornish boiler has a greater heating 
surface than the plain cylindrical boiler, and it 
has the further advantage that that portion of the 
shell on which the scale is deposited is the coolest 
instead of the hottest point. It has the disad- 
vantage that for the same water capacity it must 
have a greater diameter. 

The Galloway boiler, being virtually a modified 
' Lancashire boiler, possesses all of its advantages; 
and, additionally, on account of the conical tubes, 
which are placed transversely in the flues, it has a 
greater heating surface and better circulation. 
Furthermore, the flues are much less liable to 



STEAM ENGINEERS AND ELECTRICIANS. 6 

collapse. All of this is accomplished by the 
Galloway tubes. Of the three boilers mentioned, 
the Galloway type is the safest and most economi- 
cal in the use of fuel. 

Q. What methods are employed to stiffen the 
flues of boilers and to provide for linear expansion 
and contraction ? 

A. This end was formerly accomplished by 
making the flues in short lengths and connecting 
them by U-shaped rings, riveted on each section 
of flue. The stiffening of the flue alone is also 
accomplished by placing (J -shaped rings within 
the flues, at intervals, and by the use of Galloway 
tubes. This, however, does not take care of 
expansion and contraction. The best way of 
accomplishing both ends is by corrugating the flue, 
which has the further advantage of increasing the 
heating surface without taking up any more space 
in the boiler. 

Q. What is meant by fire-tube or tubular 
boilers ? 

A. Fire-tube or tubular boilers are those in 
which the combustion gases pass, not only around 
the outside shell, but also through tubes which are 
surrounded by water. 

Q. In what respect do they differ from flue 
boilers ? 

A. In no essential feature, except that instead 



4 QUESTIONS AND ANSWERS FOR 

of one flue of large diameter there are a number 
of small flues or tubes. 

Q. What is the difference between internally 
and externally fired tubular boilers? 

A. The internally fired type consists of an ex- 
ternal cylindrical shell containing a furnace extend- 
ing from the front of the boiler to a point about 
midway in the length of the boiler. From this 
point, and extending to the rear end of the boiler, 
there are a number of tubes which lead the gases 
of combustion to the back, whence they pass 
under the outside shell to the front and into the 
stack. In the externally fired type the tubes 
extend the whole length of the boiler, and the 
furnace is outside and under the front end of the 
boiler. The products of combustion pass along 
the bottom of the shell to the back of the boiler, 
and then return through the tubes to the front 
where they enter the stack connection. This latter 
type is frequently called the " Return Tubular." 

Q. What advantages does a tubular boiler pos- 
sess over the cylinder and flue boilers ? 

A. The tubular takes up less room, generates 
steam more rapidly, and requires less fuel ; more- 
over, tubes are less dangerous than flues, on 
account of their small diameter and great strength. 

Q. Why are tubular boilers more economical 
than plain cylinder and flue boilers ? 



STEAM ENGINEERS AND ELECTRICIANS. D 

A. Because their heating surface is much 
greater, and consequently the greater portion of 
the heat contained in the combustion gases is 
imparted to the water. 

Q. What are their disadvantages as compared 
to the above-mentioned types ? Are they impor- 
tant ? 

A. The disadvantages are that the first cost is 
greater, and that they are more difficult to clean 
and repair, because they are less accessible. These 
disadvantages are unimportant compared to the 
great gain in economy. 

Q. What may be said about the tubular boiler 
in regard to safety ? 

A. The tubular boiler is just as safe as the 
cylindrical boiler, and more so than the flue boiler, 
because the parts subjected to internal pressure 
have the same strength, while those subjected to 
external pressure, being smaller in diameter, are 
much stronger. 

Q. What is a water- tube boiler? 

A. It is one in which the water circulates 
through a series of tubes, which are surrounded 
by the combustion gases. 

Q. What is the position of the tubes in this 
class of boilers ? 

A. Different makers place the tubes in different 
positions. In the most common type, such as the 



6 QUESTIONS AND ANSWERS FOR 

Babcock and Wilcox, Heine, Gill, and Root, the 
tubes are inclined ; in others, such as the Cahall, 
they are vertical, and occasionally they may even 
be found curved spirally. 

Q. What are the principal advantages of the 
water-tube boiler as compared with other types ? 

A. Its advantages are that it is safer, more 
economical, steams more rapidly, is easily repaired, 
more durable ; its form may be adapted to almost 
any existing conditions, and it may be easily 
taken apart and transported. Its only disadvan- 
tages are that it is heavy and expensive. 

Q. Why is it durable? 

A. Because it is easily accessible, and because, 
as already stated, it adapts itself to the varying 
expansion and contraction without producing 
undue strains ; further, the circulation is good, 
and consequently the temperature of the different 
parts is fairly uniform. 

Q. To what class do locomotive and marine 
boilers belong? 

A. They may be said to belong to the tubular 
type, but they have certain characteristics not 
found in the ordinary tubular boiler, which 
really place them in separate classes by them- 
selves. 

Q. Give a. brief description of a modern marine 
boiler. 



STEAM ENGINEERS AND ELECTRICIANS. 7 

A. It usually consists of a short, circular shell 
of large diameter, with an internal corrugated 
furnace. At the back of the furnace is a chamber 
into which the gases pass from the furnace. This 
is called the back up-take. A similar chamber in 
the front, called the front up-take, connects with 
the stack. The tubes are placed above and around 
the furnace, and extend from the front to the back 
up-take. 

Q. What, then, is the essential difference be- 
tween a marine boiler and an internally fired 
tubular boiler ? 

A. The principal difference is that while in the 
ordinary internally fired tubular boiler the gases 
pass from the furnaces through tubes to the back 
and then along the outside to the front, in the 
marine boiler the gases do not pass around the 
outside at all, but go from the furnace directly 
into the back up-take, thence through the tubes 
to the front up-take and into the stack. 

Q. What conditions have brought about this 
design of boiler for marine purposes ? 

A. For marine purposes a boiler must be short, 
as otherwise it could not be set and operated in 
the available space ; and it must be self-contained, 
because brick setting, on account of its great 
weight and the motion of the ship, would be out 
of the question. It must also make steam rapidly. 



c5 QUESTIONS AND ANSWERS FOR 

Q. Are marine-type boilers ever used for sta- 
tionary purposes ? 

A. Yes; where the vibration is so great as to 
make it impossible to make use of a brick setting. 

Q. Describe briefly a locomotive boiler. 

A. A locomotive boiler consists of a lon«: cylin- 
der that contains a large number of tubes, at 
one end of which is the fire-box or furnace, fre- 
quently made of copper, in which the grate bars 
are contained. The shape of the fire-box and 
the end of the boiler shell which incloses it is 
rectangular. 

Q. What is the path followed by the products 
of combustion ? 

A. They first strike a fire-brick arch, which 
deflects them into the tubes through which they 
pass into the funnel or smoke-stack placed at the 
front end. 

Q. How is sufficient draft obtained ? 

A. In the case of the actual locomotive, by 
exhausting steam from the cylinders into the fun- 
nel. When this type of boiler is used for station- 
ary work, a sufficiently high stack is employed to 
give the necessary draft. 

Q. How are the flat surfaces of the fire-boxes 
made sufficiently strong in this type of boiler ? 

A. By short stay-bolts that are connected with 
the outside shell of the boiler. 



STEAM ENGINEERS AND ELECTRICIANS. 9 

Q. How is steam taken from locomotive boilers ? 

A. Usually from a steam dome that is placed 
on top of the boiler shell. 

Q. Why is this steam dome used ? 

A. To make sure of obtaining dry steam. 

Q. Is any other arrangement used ? 

A. Yes ; dry pipes. 

Q. What do you mean by a one horse-power 
boiler ? 

A. One which evaporates 30 pounds of water 
per hour from a temperature of 100° Fahr. to 
steam at a pressure of 70 pounds. 

Q. What materials are used for boiler shells ? 

A. Wrought iron and steel, mostly the latter. 

Q. Why is steel better ? 

A. Because it is lighter for the same strength, 
and therefore a thinner plate may be used which 
makes the heating surface more efficient. 

Q. What is the difference between longitudinal 
and curvilinear rivets ? 

A. The longitudinal rivets are those that run 
lengthwise of the boiler, and the curvilinear are 
those that run around the circumference of the 
shell. 

Q. What is the first duty of a fireman in taking 
charge of a boiler ? 

A. He should examine the water and see if it 
is at a proper level. 



10 QUESTIONS AND ANSWERS FOR 

Q. At what level should the water stand in a 
gauge-glass ? 

A. It should be kept up to the second gauge 
while working, and at night should be raised to 
the third gauge. 

Q. Why should the level of the water be raised 
at night? 

A. To insure against the water becoming too low 
from leakage or evaporation. 

Q. Suppose the water should become danger- 
ously low, what should the fireman do ? 

A. He should at once draw the fire and allow 
the boiler to cool. 

Q. Should he admit any cold water to the boiler ? 

A. On no account. 

Q. Should he attempt to raise the safety valve 
in order to diminish the steam pressure? 

A. Never ; as this would be positively danger- 
ous. 

Q. Why is it dangerous to raise the safety 
valve ? 

A. Because this would suddenly lessen the 
pressure in a boiler, and the water would be per- 
mitted to rise and perhaps come in contact with 
the overheated iron, which might cause an ex- 
plosion. 

Q. Suppose the water supply should be cut off 
for a short time, how should the fireman proceed ? 



STEAM ENGINEERS AND ELECTRICIANS. 11 

A. He should cover his fire with fresh coal, and 
shut off all steam engines or other steam-using 
devices. 

Q. In getting up steam, how should the fire- 
man proceed ? 

A. First, he should find out if the water is at a 
proper lev^el, trying the gauge-cocks for this pur- 
pose, remove all ashes and cinders from the fur- 
nace, and then cover the grate with a thin layer 
of coal. He should then place wood and shavings 
on the coal, after which he can start the fire. 

Q. Why is it advantageous to place a little cov- 
ering of coal on the grate before putting on the 
wood and the shavings ? 

A. It protects the cold grate bars from the heat 
of the fire and it also saves fuel, since the heat 
that would be transmitted to the bars is absorbed 
by the coal. 

Q. Is there any advantage in starting the fire 
gradually and slowly when commencing to get up 
steam from cold water ? 

A. Yes; it allows the parts of the boiler to ex- 
pand equally, and therefore it throws less strain 
on these parts. 

Q. How should a fireman regulate his fire ? 

A. He should keep the fire at a uniform thick- 
ness over all parts of the grate, not allowing any 
bare spots or any accumulations of ashes or dead 



12 QUESTIONS AND ANSWERS FOR 

coals at any part of the furnace; he should supply 
the coal in small quantities at frequent intervals; 
he should avoid excessive firing as much as pos- 
sible, as it is always attended with more or less 
danger, since the intense heat repels the water 
from the surface of the iron and this causes the 
plates to burn. 

Q. How thick should the fire be ? 

A. This depends upon the capacity of the 
boiler relative to the engine and upon the coal 
used. If anthracite coal be used, the thickness of 
about 3 inches is proper, and for soft coal about 5 
inches. If the boiler is too small for the work, 
it will be necessary to keep the fire thin; if, how- 
ever, the boiler is extra large, the thickness of the 
fire makes little difference. 

Q. Suppose from any cause the fire becomes 
very low, what should the fireman do ? 

A. He should place shavings, sawdust, wood, 
or other very combustible substances on the bare 
spot with a thin covering of coal and then open 
the draft to its full extent. He should not poke 
or disturb the fire, as this is likely to put it out. 

Q. Is the regulation of the draft of a furnace of 
much importance ? 

A. Yes; it is next in importance to the regula- 
tion of water, because by poor regulation of the 
draft enormous quantities of coal are wasted. 



STEAM ENGINEERS AND ELECTRICIANS. 13 

Q. How should the draft be regulated in order 
to obtain best results from the fuel ? 

.4. There should be no more draft at any time 
than would produce sufficient combustion to keep 
the steam at the working pressure; any greater 
supply of air than this carries great quantities of 
heat into the chimney, which is lost. 

Q. Can this principle of regulation be carried 
out always? 

A. Not unless the furnace and the boilers are 
sufficiently large to do their work without forcing; 
if the boiler is too small, it is impossible to use 
the fuel economically. 

Q. Why should the ashpit be kept clean ? 

A. Because if it is filled with ashes and cinders, 
the grate bars become overheated and may be 
either badly warped or melted. 

Q. Is it objectionable to throw steam or water 
under the grate bars of boilers ? 

A. Yes; because water forms with the ashes a 
lye that corrodes the iron. 

Q. What care should the fireman give to the 
safety valve ? 

A. He should keep it at all times in good work- 
ing order and should try it at least once a day, 
preferably in the morning, so as to see that all the 
parts are in good working order before getting up 
steam. 



14 QUESTIONS AND ANSWERS FOR 

Q. In filling boilers, why is a cock or valve in 
the steam room of the boiler often open ? 

A. In order to allow the air to escape so that it 
may not collect in the steam room, thus retarding 
the entrance of the water and preventing the reg- 
ular expansion of the iron after the fire is started. 

Q. Explain what you mean by the steam room 
of the boiler. 

A. That portion of the boiler occupied by steam 
above the water. 

Q. What do you mean by the fire line of the 
boiler? 

A. The line above which the fire cannot rise 
because of the masonry which surrounds the 
boiler. 

Q. How often should boiler flues and tubes be 
cleaned ? 

A. At least once a week. 

Q. Should the outside shell of the boiler also 
be cleaned? 

A. Yes. 

Q. What is the advantage gained by cleaning 
the flues frequently and the removing of soot and 
ashes from the boiler shell and tubes ? 

A. It saves fuel ; it also saves the burning of 
the tubes or plates. 

Q. How often should the fireman clean his 
boilers ? 



STEAM ENGINEERS AND ELECTRICIANS. 15 

A. This depends upon the kind of water used ; 
but no matter how good the water, he should 
clean his boiler at least every three months. 

Q. What is the duty of a fireman in regard to 
blowing out his boilers ? 

A. He should 1 blow them out regularly and 
carefully; the condition of the feed water being 
what determines how often this should be done. 
In blowing them out the dampers should be closed 
and the fire drawn. Then as much time as pos- 
sible should be allowed the boiler to cool off 
before opening the blow-off cock. An entire day 
is not too much to allow for cooling. 

Q. Why is it bad practice to blow off a boiler 
while hot ? 

A. Because in cooling without any water un- 
equal strains are liable to be produced, and also 
the scale and mud become hardened by the heat 
and stick to the boiler, thus defeating the object 
for which the boiler is blown off — namely, the 
removal of scale and mud. 

Q. What else should be done at the time of 
cleaning the boilers ? 

A. The fireman should examine all the seams 
and stays and rivets, crown sheet, etc. , and should 
also sound the shell of the boiler with a very 
light steel hammer, in order to determine the con- 
dition of the iron. 



16 QUESTIONS AND ANSWERS FOR 

Q. How often should the steam gauge be tested ? 

A. At least once a year. 

Q. Can the fireman usually test the steam gauge 
himself ? 

A. Not unless he has access to a test gauge, 
which is not often the case. 

Q. How can the fireman clean his water-gauge 
glass inside? 

A. Open the drip-cock and close the water valve 
which will allow the steam to rush down the 
glass and carry out any dirt that is in it. When 
the boiler is cool, the glass can also be swabbed 
out with a piece of cloth on a stick. 

Q. Is it advisable to use a piece of wire or iron 
instead of a stick ? 

A. No ; as it is likely to crack the glass. 

Q. What can you say about the care of the 
gauge cocks ? 

A. They should be examined several times a 
day, to make sure that they are in good working 
order ; they should be shut tight, and should be 
ground or repaired whenever necessary so as to 
make them tight. 

Q. What Avould you do in cold weather if you 
thought that your pumps, boiler connections, or 
water pipes were liable to be frozen ? 

A. I would open all drip- or discharge-cocks 
and allow the water to run out of them when I 



STEAM ENGINEERS AND ELECTRICIANS. 17 

stopped work at night. In the morning I would 
examine all the steam- and water-connections be- 
fore starting the fires. 

Q. What would you do in case it becomes 
necessary to stop the engine and steam should 
commence to blow off at the safety valve ? 

A. I would immediately start the pump or 
injector and cover the fire with fresh coal. 

Q. Is it desirable to have the damper open at 
the same time as the fire door ? 

A. No ; the door and damper should never be 
open at the same time, because the cold air would 
rush through the open door above the fire and 
strike on the tube and crown sheets, which would 
be liable to contract the seams and cause leakage. 

Q. How would you proceed if you wished to 
examine the check valve while the steam is on the 
boiler ? 

A. I would first close the stop-cock between the 
check valve and boiler ; then I would unscrew 
and remove the check. 

Q. Describe how you would make a joint on 
the manhole or handhole of the boiler. 

A. I would first remove all gum or other ma- 
terial from the seat flange where the joint is to be 
made, and would then put on the gasket and 
tighten the nut. 

Q. How often should you consider that a good 



18 QUESTIONS AND ANSWERS FOR 

fireman should make a thorough examination of 
everything under his charge ? 

A. He should, at least once a day, make a 
thorough examination of all safety valves, pumps, 
injectors, steam- and water-connections, etc. 

Q. What is scale in a boiler ? 

A. It is a deposit that forms on the inside of a 
boiler shell or tubes. 

Q. From what does this deposit come ? 

A. From impurities in the feed water. 

Q. What are the results of scale in boilers ? 

A. It increases the coal consumption and causes 
burning of the plates. 

Q. Why does it increase the coal consumption ? 

A. Because the scale being a poor conductor of 
heat, the heat of the fire is not imparted to the 
water as completely as if the water was directly 
in contact with the plate. 

Q. Why does the deposition of scale increase 
the tendency of the plates to burn ? 

A. The water, not being directly against the iron, 
does not protect it from crystallization or burning. 

Q. How can the formation of scale be guarded 
against ? 

A. In two ways : first, by depositing the im- 
purities in water in feed-water heaters of the open 
type before the water gets into the boiler ; second, 
by the use of boiler compounds in the boiler. 



STEAM ENGINEERS AND ELECTRICIANS. 19 

Q. Is there any boiler compound that will be 
effective in all cases ? 

A. No ; the composition of the compounds 
should be varied according to the nature of the 
impurities that are contained in the feed water. 

Q. What is corrosion ? 

A. Corrosion is the w r asting or pitting of iron in 
the boiler. 

Q. To what is it generally due ? 

A. Corrosion on the outside of a boiler is gener- 
ally due to the chemical action of sulphur or other 
impurities in the fuel or in the atmosphere. Cor- 
rosion on the interior of the boiler is caused by 
the chemical action of acid or mineral substances 
in the feed water. 

Q. What remedies are employed to prevent 
corrosion ? 

A. The interior of the boiler is often painted 
with a thin coating of Portland cement ; another 
method is to allow a thin layer of scale to form; 
still another method is to suspend metallic zinc in 
the water and steam spaces. 

Q. What is foaming, and w T here would it be 
noticed ? 

A. Foaming is a violent movement of the 
water ; it is noticed at the gauge glass by the 
rapid rise and fall of the w r ater level. 

Q. What causes foaming in boilers ? 



20 QUESTIONS AND ANSWERS FOR 

A. Foaming may be clue to poor design of the 
boiler that has provided an insufficient amount of 
steam space. If the boiler is properly designed 
in this respect, foaming will be due to the foul 
condition of the boiler or to the presence of some 
soapy or greasy substance in the feed water. 

Q. Is foaming a source of danger ? 

A. Yes; when a boiler foams badly the water is 
lifted from the fire surface of the boiler, which 
allows the iron to be burned. 

Q. Is there any danger to the engine in case of 
foaming ? 

A. Yes ; mud and water from the boiler are 
liable to be carried into the cylinder of the engine, 
and either scratch the cylinder surface or perhaps 
cause the breaking of the cylinder head. 

Q. What steps should you take to prevent 
foaming ? 

A. I would check the boiler and endeavor to 
obtain pure feed water. 

Q. What is priming? 

A. Priming is the carrying over of water from 
the boiler to the engine in the form of spray. 

Q. What causes priming? 

A. Sometimes a lack of sufficient steam space 
in the boiler, but if properly designed in this re- 
spect it will be due to carrying the water at a too 
high level. 



STEAM ENGINEERS AND ELECTRICIANS. 21 

Q. For what is a safety valve used ? 

A. It is intended to protect the boiler from ex- 
plosion by relieving the pressure of the boiler 
whenever it gets beyond a certain amount. 

Q. What is the general principle on which a 
safety valve works ? 

A. The steam pressure in the boiler is balanced 
against the pressure of a spring or weight in such 
a manner that when the pressure in the boiler ex- 
ceeds a safety limit it will overcome the action of 
the spring or weight and open the valve. This 
allows the escape of steam and thus diminishes 
the pressure. 

Q. What is the effect of the continual action of 
the steam on the safety valve ? 

A. The valve becomes worn and leaky and must 
be occasionally ground on the seat. 

Q. What material would you use for the grind- 
ing? 

A. Powdered glass, grit from grindstones, or 
fine emery. 

Q. How often would you test a safety valve, 
and when ? 

A. At least once a day — in the morning — so as 
to be sure that it is in good working order before 
starting the fire. 

Q. What classes of safety valve are you familiar 
with? 



22 QUESTIONS AND ANSWERS FOR 

A. Three classes: first, the dead-weight safety 
valve, in which the weight that balances the pres- 
sure of the steam is placed directly on the valve 
spindle ; second, a spring safety valve, which is 
like the first except that the spring takes the place 
of the weight ; third, the lever safety valve, in 
which the weight or spring, instead of being 
placed directly on the valve spindle, is attached to 
a lever. 

Q. How are the adjustments made with a lever 
valve ? 

A. By altering the position of the weight or 
spring on the lever. 

Q. How many safety valves should a boiler 
have ? 

A. At least two. 

Q. What are the principal gauges used in con- 
nection with steam boilers ? 

A. The water gauge, pressure gauge, and vac- 
uum gauge. 

Q. When there is no steam on the boiler, where 
should the pointer of the pressure gauge stand ? 

A. At zero. 

Q. Suppose that it does not stand at zero ? 

A. It should be adjusted by comparison with a 
standard gauge. 

Q. What is a water gauge ? 

A. An apparatus for showing the level at which 



STEAM ENGINEERS AND ELECTRICIANS. 23 

water stands in a boiler. It consists of the glass 
tube placed on the outside of the boiler, the top 
end being connected to the steam space and the 
bottom end to the water space. 

Q. What is a safety water column ? 

A. A modification of the water gauge, consist- 
ing of floats so arranged that a signal is given 
whenever the water is too high or too low. 

Q. Is it safe to depend upon the indications of 
the safety water column ? 

A. No; while they are useful as an additional 
safeguard in maintaining the proper level of the 
water, a fireman must on no account neglect to 
watch the level in the water gauge. 

Q. What other device is used for finding out 
the water level ? 

A. Gauge cocks (usually three in number) 
placed at different levels. 

Q. How often should these gauge cocks be 
tried, and why ? 

A. Several times a day, because the gauge-glass 
connections may become choked and cause the 
glass to give incorrect indications of the level of 
the water. 

Q. What are pumps, and how are they usually 
operated ? 

A. Pumps are machines for lifting or transfer- 
ring water or other liquids. They are operated 



24 QUESTIONS AND ANSWERS FOR 

either by belting, by steam, or by connection to 
an electric motor. 

Q. Which of the above types is usually em- 
ployed for boiler-feed pumps ? 

A. The steam pump. 

Q. What different kinds of steam pumps are 
there ? 

A. Fty-wheel pumps, direct- acting pumps, and 
duplex pumps. 

Q. Which of these pumps is most commonly 
used for a boiler-feed pump, and why ? 

A. The duplex pump, because it is the simplest. 

Q. What is a duplex pump ? 

A. Duplex pumps consist of a combination of 
two steam pumps so coupled together that the 
steam valve of one is operated by the piston of the 
other. 

Q. Explain the difference between a force pump 
and a suction pump. 

A. A force pump is one that forces the water 
against some opposing pressure, such as the pressure 
in the boiler; and a suction pump is one that takes 
water from a level below that of the pump and 
raises it — as, for example, an ordinary well pump. 

Q. Is there any limit to the height to which a 
suction pump will draw water? 

A. Yes; it cannot lift water more than 33 feet 
vertically. 



STEAM ENGINEERS AND ELECTRICIANS. 25 

Q. Is there any limit to the height to which a 
pump will force water ? 

A. Xone, except the power of the pump. 

Q. What is an injector ? 

A. An apparatus for forcing water against a 
pressure by the direct action of a jet of steam 
on the water. 

Q. Injectors frequently fail to operate. What 
is the common cause of this failure ? 

A. The presence of air in the suction pipe. 

Q, How would you avoid this ? 

A. I would make sure that the end of the suc- 
tion pipe was entirely in the water, that the valve 
stem was properly packed, and that there was no 
sediment or dirt in the nozzle. 

Q. If an injector was not getting water, where 
would you look for trouble ? 

A. I would first examine the water pipe, then 
see if the strainer was clogged; then, if the trouble 
were due to neither of these, it might be due to too 
hot water or too low a steam pressure. 

Q. If after the injector has once started the jet 
of water breaks, where would you look for the 
difficulty ? 

A. It might be due to any of the above causes 
or to a loose disc in the supply pipe valve. 

Q. What are the principal precautions to be used 
in setting up injectors ? 



26 QUESTIONS AND ANSWERS FOR 

A. All pipes must be at least as large as the 
holes in the corresponding branch of the injector, 
and must be as short and straight as possible. A 
strainer should be placed over the end of the 
water-supply pipe. The area of all holes in the 
strainer must be considerably greater than the area 
of the water-supply pipe, so as to compensate for 
the closing of some of them by deposits of sticks 
or other matter. Steam should be taken from the 
highest part of the boiler, so as to get it as dry as 
possible, as wet steam cuts the steam spindle and 
nozzle of the injector. It is not advisable to take 
steam from the engine supply pipe unless this pipe 
is very large, as the sudden variations in pressure 
may break the jet. After the injector is properly 
connected it should be thoroughly washed out by 
blowing steam through it, so as to take out all 
the red lead or any other solids that may be in the 
pipe. 

Q. Should injectors be set high or low ? 

A. As low as possible, since their capacity 
diminishes and also their reliability as to the 
height of the lift is increased. 

Q. What is an ejector ? 

A. An instrument similar to the injector, and 
designed only to lift water without forcing it 
against a pressure. 

Q. What is an inspirator ? 



STEAM ENGINEERS AND ELECTRICIANS. 27 

A. A double jet injector; one jet is used to lift 
the water, the other to force it into the boiler. 

Q. Should a boiler plant have both a pump and 
an injector? 

A. Yes; because either one may at some time 
refuse to operate. 

Q. What is the object in heating feed water 
before it goes in the boiler ? 

A. There are several reasons for doing so: first, 
because if the water were fed into the boiler cold, 
it would produce strains in the boiler which would 
tend to shorten its life; second, because heating the 
feed water to a high temperature will cause a large 
proportion of the salts contained in the solution to 
separate out and to be deposited in the heater 
instead of producing scale in the boiler; third, if 
the heater is supplied with exhaust steam or with 
some other source of heat which would otherwise 
be wasted, there is a considerable saving of fuel. 

Q. What is the difference between open and 
closed heaters? 

A. In closed heaters the exhaust steam passes 
through a series of brass tubes and the feed water 
passes through a space around the tubes and into 
the boiler; or, the opposite arrangement may be 
used, the water passing through the tubes and the 
steam around the tubes. In open heaters the 
steam comes in actual contact with the water. 



28 QUESTIONS AND ANSWERS FOR 

Q. What is an economizer ? 

A. An economizer is a device used for heating 
feed water which makes use of the products of 
composition passing from the boiler furnace into 
the stack. 

Q. How are economizers generally made ? 

A. They are usually made of a series of iron or 
steel tubes connected at each end by headers like 
those used in water-tube boilers. The feed water 
circulates through the tubes and the products of 
composition pass around the tubes. 

Q. What is a grate, and for what purpose is it 
used? 

A. A grate consists usually of a series of cast- 
iron bars supported at either end and placed in the 
furnace chamber, its object being to support the 
fuel in such a manner as to allow the free passage 
of air through the fuel. 

Q. What limits the length of the grate ? 

A. The distance to which the fireman can throw 
the coal, which is about 6 feet. 

Q. What is the object in inclining the bars 
downward toward the bridge wall ? 

A. To make the distribution of fuel more easy. 

Q. How much coal is generally consumed j)er 
square foot of grate surface ? 

A. This depends entirely upon the draft and the 
kind of coal. 



STEAM ENGINEERS AND ELECTRICIANS. 29 

Q. How much anthracite coal would you expect 
to be burned in a good stationary boiler ? 

A. About nine (9) pounds. 

Q. Roughly, how much grate surface is allowed 
per horse-power ? 

A. In stationary boilers about J- of a square 
foot. 

Q. What is a shaking grate ? 

A. It is a grate operated mechanically, which 
moves in such a way as to clean the fire, break up 
the clinkers, and remove them without opening 
the fire door. 

Q. What is the advantage of a shaking grate ? 

A. It does away with the necessity of opening 
the fire doors frequently, and since the entrance 
of cold air in the fire door tends to create strains 
in the boiler the use of the shaking grate would 
increase the durability of the boiler. Also, it is 
impossible for a fireman to thoroughly stir up 
with the slicing bar every part of the grate; there- 
fore, if the coal used had a tendency to form 
clinkers, the shaking grate would be an advan- 
tage, because all parts of the fire would be reached 
by its action. 

Q. What do you mean by automatic stoking ? 

A. Feeding the coal and removing the ashes 
from the furnace automatically without opening 
the furnace doors. 



30 QUESTIONS AND ANSWERS FOR 

Q. What advantages are claimed for mechanical 
stokers ? 

A. Saving of fuel, prevention of smoke, and 
less hand labor. 

Q. Why should a mechanical stoker save fuel ? 

A. Because the coal is spread upon the grate 
uniformly and frequently, whereas with hand 
tiring coal is fed into the furnace at irregular 
intervals, and usually more coal is put in than 
is desirable to obtain a perfect combustion ; 
moreover, each time the boiler is fired by hand 
the furnace doors must be opened, which allows 
cold air to rush in, and this current of cold air 
diminishes the effectiveness of the boiler. 

Q. Why do mechanical stokers diminish the 
production of smoke? 

A. Because the fuel is fed in small quantities 
and the motion of the grate keeps the air spaces 
open so that the combustion is at all times com- 
plete. As smoke is the product of imperfect 
combustion, it is clear that any process which 
makes the combustion better will diminish the 
amount of smoke. 

Q. Why do stokers save labor? 

A. Because there is no cleaning of fires or shov- 
eling of coal or manual labor of any kind except 
the wheeling out of the ashes. 

Q. What is the purpose of a chimney or stack ? 



STEAM ENGINEERS AXD ELECTRICIANS. 31 

A. Its purpose is to produce a draft that will 
take away from the furnaces the products of com- 
bustion and will furnish fresh air. 

Q. What kinds of coal require the tallest 
stacks ? 

A. Those that do not burn very readily, such as 
anthracites. 

Q. For what is a steam separator used ? 

A. In order to remove the moisture from steam 
before it enters the engine cylinder. 

Q. For what is a steam trap used ? 

A. In order to remove condensed steam from 
steam pipes without allowing any of the steam 
itself to escape. 

Q. If a separator or trap or heater should re- 
quire cleaning or repairing, will it be necessary to 
shut down the plant in order to do this ? 

A. In a properly designed system it would not 
be, for they should always be piped in such a way 
that steam or water may, by turning the valves, 
be made to pass temporarily through auxiliary 
pipes around the heater separator or trap. 

Q. Give a brief description of the manner in 
which a by-pass is usually constructed. 

A. See " Roper's Catechism, " page 173. 

Q. Explain how you would proceed in cleaning 
a fire. 

A. Let one side of the fire burn down, keeping 



32 QUESTIONS AND ANSWERS FOR 

the other side burning in good condition. Pull out 
the side that has burned down and knock off any 
clinkers that may be on the walls. Turn the good 
part of the fire over onto the grate bars and put on 
as much new fuel as it needs ; allow a little time 
for the clinkers and ashes on the other side to cool 
and then pull them out. 

Q. What is the purpose of a fusible plug? 

A. It is intended to melt if by any chance the 
water falls below the level of the plug. The 
melting of the plug opens a passage-way by which 
water flows into the fire-box and extinguishes the 
fire. 

Q. How is the plug made ? 

A. It is made of a brass nipple having a hexa- 
gon head on one end ; this nipple is hollow and is 
filled with a composition which remains solid as 
long as the water is in contact with it, but which 
melts at a fairty low temperature. 

Q. Where is the fusible plug usually placed ? 

A. In the top of a fire-box. 

Q. How could you tell whether or not the 
fusible plug were in proper condition ? 

A. If it were covered with scale or soot I should 
not consider it were in good condition, but if free 
from both, I should consider it to be all right. 

Q. How can you tell a high pressure from a 
low pressure safety valve ? 



STEAM ENGINEERS AND ELECTRICIANS, 33 

A. By looking at the figures stamped on the 
valve or on the lever. On low pressure valves 
the figures will not run higher than about 30 
pounds. 

Q. In what way could you judge whether the 
safety valve of a boiler were in good condition or 
not? 

A. If it opened always at the same pressure and 
never showed any indication of sticking, I should 
assume that it were in good condition. 

Q. What is a steam damper regulator and how 
does it work ? 

A. It is an apparatus for regulating the position 
of the damper by the pressure of steam in the 
boiler. The general arrangement is to have the 
damper connected with a water pressure. The 
steam pressure in the boiler controls a valve not 
unlike a safety valve which admits or releases the 
water pressure according as the steam pressure is 
too high or too low. 

Q. What checks have you on the accuracy of 
the steam gauge ? 

A. If the gauge reading corresponds with the 
position at which the safety valve blows off or 
with the position of the damper regulator it would 
show that the gauge were accurate. 

Q. How can you tell whether the blow-off valve 
is leaking or not ? 
3 



34 QUESTIONS AND ANSWERS FOR 

A. If it is leaking, the pipe will be hot outside 
of the valve. 

Q. How is the feed water for a boiler regulated 
with a power pump ? 

A. By means of the by-pass on the pump. 

Q. How is the feed regulated with a steam 
pump ? 

A. If the pump takes water from a water system, 
it is regulated by means of the throttle valve of 
the pump. If it takes water from a receiver into 
which the returns from a heating system flow 
together with city water, it is controlled by the 
cold-water valve on the receiver. 



STEAM ENGINEERS AND ELECTRICIANS. 35 

QUESTIONS FOR STATIONARY 
ENGINEERS. 

Engineers should also be prepared to answer any of the 
"Questions for Firemen." 

Q. What do you mean by the term "a one 
horse-power steam boiler ' ' ? 

A. A one horse-power boiler is one which 
would, under ordinary conditions, supply as 
much steam as would be consumed in an aver- 
age steam engine producing one horse-power. 

Q. Is there no more definite rating than this 
for the horse-power of boilers ? 

A. Yes; generally, the horse-power of boilers 
is based on a capacity for evaporation of 30 
pounds of water per hour from feed water at a 
temperature of 100° Fahr. to steam at a pressure 
of 70 pounds. 

Q. What is this method of rating called ? 

A. It is known as the Centennial Rating, be- 
cause it was determined upon by the Committee 
of Judges at the Centennial Exhibition in 1876. 

Q. Does the horse-power of steam boilers cal- 
culated according to this rule come near to the 
actual consumption of steam in ordinary steam 
engines ? 

A. It is about right for an automatic cut-off, 
high-speed, non-condensing engine. For plain 



36 QUESTIONS AND ANSWERS FOR 

slide valve engines using a throttling governor the 
rating is much too low, while for compound and 
condensing engines it is too high. 

Q. In choosing a boiler, how would you deter- 
mine upon the proper size, assuming that the 
horse-power is based upon the Centennial Rating ? 

A. I would in any case have the boiler capacity 
somewhat in excess of that of the engine, because 
the evaporative power of the boiler will diminish 
with use owing to the accumulation of scale. 

Q. Is there any disadvantage in using a boiler 
larger than is strictly necessary to evaporate the 
necessary amount of steam ? 

A. No; the efficiency of a boiler is not lessened 
by operating it below its maximum capacity, 
wherein the boiler differs materially from the 
steam engine. 

Q. What horse-power boiler would you use for 
an automatic cut-off, single expansion, and non- 
condensing engine of 100 horse-power? 

A. I would use a boiler of 130 to 140 horse- 
power based upon the Centennial Rating. 

Q. Suppose the engine was used with a con- 
denser ? 

A. Then a 100 horsepower boiler would be 
sufficient. 

Q. Suppose the engine were a plain slide valve 
with throttling governor? 



STEAM ENGINEERS AND ELECTRICIANS. 37 

A. I would then use a boiler of 160 horse- 
power. 

Q. Suppose the engine used was a Corliss type, 
non-condensing ? 

A. I would then use a boiler of about 100 horse- 
power. 

Q. What is the effect on the evaporative ca- 
pacity of a boiler of lowering the temperature of 
the feed water ? 

A. It diminishes the capacity of the boiler. 

Q. Can a boiler of given size evaporate as many 
pounds of water per hour to a pressure of 100 
pounds as to a pressure of 70 pounds ? 

A. No; it will evaporate much less water. 

Q. What is meant by the evaporative efficiency 
of a boiler ? 

A. The number of pounds of steam that it will 
generate for each pound of fuel consumed. 

Q. What evaporative efficiency would you 
expect from the various types of boilers ? 

A. From flue boilers, from 6 to 8 J- pounds; 
from tubular boilers, from 8 to 10 pounds; from 
water- tube boilers, from 10 to 11 pounds of w r ater 
per pound of coal. 

Q. Are the average results as good as these ? 

A. No; they are probably 25 per cent, lower. 

Q. Upon what does the grate surface in boilers 
depend ? 



38 QUESTIONS AND ANSWERS FOR 

A. Mostly upon the quality of coal and the 
draft. 

Q. Is it well to have the grate surface too large ? 

A. No; not so large that the air passing through 
it will greatly exceed the amount necessary for the 
- complete combustion of the fuel. 

Q. How many pounds of coal can be consumed 
per square foot of grate surface ? 

A. From 4 to 120 pounds, depending on the 
coal and the draft. 

Q. What do you mean by heating surface ? 

A. The total area of all those parts of the 
boiler that come in contact on one side with the 
flame or products of combustion, and on the other 
side with water or steam; that is, it is all that part 
of the surface through which the heat of the fire 
is transmitted to the water or steam. 

Q. Give a rule by which you could calculate the 
heating surface of the cylinder boiler. 

A. Multiply § of the circumference of the shell 
in inches by its length in inches, add the area of 
one end expressed in square inches and divide by 
144; the quotient will be the number of square 
feet of heating surface. 

Q. How would you calculate the heating surface 
for horizontal tubular boilers ? 

A. Multiply § of the circumference of the shell 
in inches by its length in inches; multiply the 



STEAM ENGINEERS AND ELECTRICIANS. 39 

combined circumference of all the tubes in inches 
by the length of one of them in inches; to the sum 
of these two products add § of the area of both 
tube sheets; from this sum subtract the combined 
area of the cross-section of all the tubes;, divide 
the remainder by 144, and the quotient will be 
the number of square feet of heating surface. 

Q. How much heating surface per horse-power 
is provided in fire- and water-tube boilers ? 

A. From 12 to 15 square feet. 

Q. Could you then calculate approximately the 
horse-power of any tube boiler ? 

A. Yes; by calculating the heating surface in 
square feet and dividing it by 12. 

Q. What is the average ratio between the grate 
surface and heating surface in stationary boilers ? 

A. About 35 feet of heating surface to 1 square 
foot of grate surface. 

Q. How much good anthracite coal can be con- 
sumed per square foot of grate under ordinary 
conditions ? 

A. About 11 pounds. 

Q. How much coal per horse-power per hour 
would you expect to be consumed if the boiler 
were a good water-tube boiler and the engine were 
a simple, high-speed, automatic cut-off engine 
used without a condenser ? and explain how you 
arrive at this figure. 



40 QUESTIONS AND ANSWERS FOR 

A. I should expect the water-tube boiler to 
evaporate 10 pounds of water per pound of coal; 
I should expect the engine, if of good size, to use 
about 45 pounds of water per horse-power per 
hour; therefore, I should expect a coal consump- 
tion of about 4^ pounds per horse-power per hour. 

Q. What materials are principally used now for 
making boiler shells ? 

A. Wrought iron and steel, of which the latter 
is more widely used. 

Q. Why is steel replacing wrought iron ? 

A. Because it is lighter for a given strength and 
therefore, since a thinner plate may be used, the 
efficiency of the heating surface is better. 

Q. What considerations would guide you in 
determining upon the proper thickness of boiler 
plate? 

A. First, the question of safety; second, dura- 
bility ; third, economy. As to safety, the thick- 
ness depends upon the quality of iron, diameter 
of boiler, and pressure to be carried. As to dura- 
bility, the thickest metal is not necessarily the 
best, since the outside of the sheet becomes burned 
and crystallized, and in general gives less wear 
and satisfaction than the thinner gauge. As to 
economy, obviously the thinner sheets are better. 

Q. Give some figures as to the range of thick- 
ness of boiler iron or steel. 



STEAM ENGINEERS AND ELECTRICIANS. 41 

A. The thickness should in general range be- 
tween -§- and T 3 g- of an inch. 

Q. What special properties should a material 
possess in order to make it suitable for use in 
boiler plates ? 

A. Whether it be of iron or steel, it should 
have a tensile strength of not less than 50,000 
pounds per square inch; it should elongate 25 per 
cent, without breaking, and the contraction of 
area of cross-section at the point where breaking 
takes place in the test-piece should be 50 per cent. 
It should also stand bending without injury 
around a radius equal to the thickness of the plate. 

Q. What do you mean by longitudinal and 
curvilinear rivets ? 

A. By the first, I mean those that run length- 
wise of the boiler ; by the second, those that run 
around the circumference of the shell. 

Q. Is the pressure on all seams the same ? 

A. No; on the longitudinal it is nearly double 
what it is on the curvilinear, and for this reason 
the longitudinal seams are double riveted. 

Q. Does a boiler plate lose any of its strength 
by riveting? 

A. Yes; about 45 per cent, if single riveted, 
and about 30 per cent, if double riveted. 

Q. What determines the proper diameter for 
rivets ? 



42 QUESTIONS AND ANSWERS FOR 

A. The diameter of the boiler, thickness of 
iron, and the pressure to be carried. 

Q. Give some rough figures for the diameter of 
rivets. 

A. Rivets generally vary from § to f of an inch 
in diameter. The larger the diameter of the 
boiler and the thicker the plate, the greater should 
be the diameter of the rivet. 

Q. Which is the better method of riveting 
boilers, by hand or by machine ? 

A. If thick plates, machine work is much supe- 
rior, as the power of the machine brings the work 
together better than can be done by hand; if thin 
boiler plates, hand riveting answers very well. 

Q. Is it better to drill rivet holes in boilers in- 
stead of punching them ? 

A. Very much, as the punching of holes injures 
the strength of the plates much more than does 
the process of drilling them. 

Q. What is a drift pin ? 

A. It is a tapering steel pin, which is intro- 
duced into the holes at the seams in order to 
bring them into line. 

Q. Is the use of the drift pin advisable ? 

A. No; it should be dispensed with as much as 
possible, as a reckless use of it often results in 
great injury to the boiler plates. 

Q. How can its use be avoided ? 



STEAM ENGINEERS AND ELECTRICIANS. 43 

A. To a great extent b}^ the careful laying out 
of the holes in the sheet and drilling or punching 
them with good judgment ; the holes will then 
come together so closely that they can be straight- 
ened by the use of the reamer without having 
recourse to the drift pin. 

Q. What is the effect of hammering on the 
quality of iron ? 

A. It injures it, making it harder and more 
brittle. 

Q. What is the effect of rolling ? 

A. Rolling adds to the toughness of the iron. 

Q. When a boiler is under steam, is the pressure 
equal on all sides of the shell ? 

A. No; the pressure on the lower side is greater 
than the upper side of the boiler by the weight of 
the water. 

Q. Is there any danger of injuring boilers by 
application of the cold-water or ' ' hydrostatic ' ' 
test? 

A. Yes; a reckless use of this test has often 
resulted in injury to the boilers. 

Q. Would the shell and flues be stronger under 
a cold-water pressure of, say, 80 pounds to the 
square inch than under same steam pressure ? 

A. No; because iron increases in strength with 
the increase of temperature up to about 550° 
Fahr. 



44 QUESTIONS AND ANSWERS FOR 

Q. How would you calculate the safe working 
pressure ? 

A. Multiply the thickness of the shell in inches 
by the tensile strength in pounds per square inch ; 
multiply one-half the diameter by the factor of 
safety and divide the first product by the second. 
and the quotient will be the safe working pressure. 

Q. What factor of safety is usually employed ? 

A. A factor varying from 3 to 5; a safe average 
for stationary boilers would be 4. 

Q. What value of tensile strength would be 
used in the rule for safe working strength ? 

A. That would depend upon the riveting of the 
joints. If single riveted, I would use about fifty- 
five hundredths (.55) of the ultimate breaking 
strength of the steel; if the joints were double 
jointed, I would take seventy hundredths (.70). 

Q. If a boiler 48 inches in diameter were made 

of steel having an ultimate tensile strength of 

55,000 pounds per square inch with double-riveted 

joints, Avhat would be the safe working pressure 

if the thickness of the shell were -§- of an inch and 

the factor of safety decided upon were 5 ? 

, _ | X 55, 000 X. 70 onn , 

A. P = xx 4 8X 5 = 200 pounds per 

square inch. 

Q. What materials are best adapted for the set- 
ting of boilers ? 



STEAM ENGINEERS AND ELECTRICIANS. 45 

A. The walls should be of hard-burned brick 
laid in Portland cement; all surfaces exposed to 
the action of the flame or heated gases should be 
lined with the best quality of fire-brick laid in a 
thin mortar of fire clay. 

Q. What should be the distance between the 
grate bars and the bottom of the boiler shell ? 

A. About 40 inches. 

Q. What should be the distance between the 
back tube sheet and the wall ? 

A. For a 48-inch shell about 24 inches, and for 
a 72-inch shell about 36 inches. 

Q. What are buckstaves ? 

A. They are vertical braces of cast or wrought 
iron, which are placed on the outside of the boiler 
walls and are held together at the top and bottom 
by tie rods. They are used to hold the boiler 
walls in place. 

Q. What are the two styles of boiler fronts ? 

A. A full-flush front, which consists of a cast- 
iron plate covering the entire front of the setting 
and leaves no brickwork in sight; and the half- 
arch front, which covers only the furnace with an 
iron plate. 

Q. Which of these two are the better ? 

A. The full-flush front. 

Q. When a number of boilers are set together, 
is it desirable that each should be set indepen- 



46 QUESTIONS AND ANSWERS FOR . 

clently from the others and that each should have 
its separate stack connection ? 

A. Yes; because each boiler can be operated and 
shut down independently of the others, and be- 
cause the draft of one is not affected by the others. 

Q. Suppose that you were asked to choose a 
boiler to be used where the vibration is excessive, 
what type of boiler would you select ? 

A. A locomotive or marine type of a boiler, be- 
cause they require no brickwork. 

Q. What are the results of the formation of 
scale in boilers ? 

A. The scale produces burning of the plates and 
an increased coal consumption. 

Q. Why is this? 

A. Because the scale is a poor conductor of heat, 
and therefore the water does not protect the plate 
against crystallization and burning, and also the 
heat of the fire is not imparted to the water as 
advantageously as if the scale were not present. 

Q. Roughly, how does the conductivity of scale 
compare with that of iron ? 

A. It is about -j^ of that of iron. 

Q. What are the principal ingredients contained • 
in water that go to cause the formation of scale ? 

A. They are sulphate of lime, phosphate of 
lime, carbonate of lime, magnesia, silica, and 
alumina. 



STEAM ENGINEERS AND ELECTRICIANS. 47 

Q. Which is the most important of these exist- 
ing in sea- water ? 

A. Sulphate of lime. 

Q. What are boiler compounds ? 

A. Boiler compounds are chemical substances 
of various kinds that are employed in order to 
check the formation of scale. 

Q. Will any one boiler compound be effective 
in all cases ? 

A. No; to be effective the composition of the 
compound must be suited to the nature of the 
impurities. 

Q. Suppose that the principal ingredient in the 
water tending to produce scale were sulphate of 
lime, what substance would you use ? 

A. Carbonate of soda. 

Q. What would be the best thing to do if it 
were found that a large amount of scale formed in 
boilers under your charge ? 

A. It would be best to have an anatysis of the 
feed water made by a chemist, so that knowing 
what scale-producing substances are present we 
could add sufficient quantities of proper materials 
to change the scale producers into soluble salts. 

Q. In what other way can formation of scale in 
boilers be largely prevented ? 

A. By the use of feed- water heaters and puri- 
fiers of the open type. 



48 QUESTIONS AND ANSWERS FOR 

Q. How does this remedy the difficulty ? 

A. By depositing the impurities in the heater 
where they can do no harm, and from which they 
can be easily removed, instead of in the boiler 
itself. 

Q. What do you mean by foaming in a boiler ? 

A. Foaming is a violent agitation of water in a 
boiler, which is shown by the frequent change of 
level of the water in the gauge glass. 

Q. What are some of the causes of foaming? 

A. Poor design of boiler, muddy water, foul 
condition of the boiler, and the presence of any 
soapy or greasy substance in the feed water. 

Q. What injury could foaming produce on the 
boiler ? 

A. When a boiler foams badly the water is 
lifted from the fire surface and this allows the 
plates to burn. 

Q. Is there any danger to the engine from foam- 
ing in the boiler ? 

A. Yes; mud and water are liable to be carried 
over with the steam into the cylinder and injure 
the surface of the cylinder and often cause the 
breaking of the cylinder head. 

Q. What do you mean by priming? 

A. The carrying over of water from the boiler 
to the engine in the form of spray. 

Q. How could you detect it? 



STEAM ENGINEERS AND ELECTRICIANS. 49 

A. By noticing the exhaust from the engine; if 
this be white instead of colorless, it would show 
that moisture is present in the steam. In such 
cases there is generally a clicking noise in the 
cylinder. 

Q. What causes priming ? 

A. Generally it is due either to the water being 
carried at too high a level in the boiler or to the 
lack of sufficient steam space. 

Q. What is a safety valve ? 

A. A valve designed to prevent explosion of 
boilers by relieving them from excessive pressure. 

Q. What is the general principle on which it is 
constructed ? 

A. The steam pressure is balanced by a spring 
or weight in such a manner that when the pres- 
sure in the boiler gets too high it overcomes the 
action of the spring or weight and opens a valve 
that allows the steam to escape. 

Q. What are the most important points to be 
looked after in the construction of safety valves ? 

A. Simplicity and freedom of action. 

Q. Should the stems be loose or rigid ? 

A, Loose, as the solid or rigid stem is liable to 
be jammed by the canting of the lever or weight, 
and in this case the higher the pressure the more 
difficult it is for the valve to open. 

Q. What three classes of safety valves are there ? 

4 



50 QUESTIONS AND ANSWERS FOR 

A. The dead-weight, spring, and lever safety- 
valves. 

Q. Which are the better to use, springs or 
weights in safety valves ? 

A. This depends upon the places in which they 
are to be used. On vessels or locomotives, weights 
could not be used on account of the motion, but 
for stationary work, weights have the advantage 
in that they do not change, while springs are 
liable to alter their strength when under tension. 

Q. How would you set a safety valve for any 
desired blow-off pressure in the dead-weight or 
spring type? 

A. By adjusting the weight or the tension of 
the spring until this weight becomes equal to the 
area of the valve in square inches multiplied by 
the pressure in pounds per square inch. 

Q. How would you calculate the weight which 
it would be necessary to put on the end of a certain 
lever safety valve for a desired blow-off pressure ? 

A. I would first multiply the area of the valve 
in square inches by the blow-off pressure in 
pounds per square inch and by the distance of 
the valve from the fulcrum in inches ; then I 
would multiply the weight of the lever in pounds 
by the distance of its center of gravity from the 
fulcrum ; then I would multiply the weight of 
the valve and stem by their distance from the ful- 



STEAM ENGINEERS AND ELECTRICIANS. 51 

crum ; after adding the last two products together 
and subtracting their sum from the first product, 
I would divide the remainder by the length of the 
lever, and the quotient will be the weight in 
pounds required. 

Q. How would you find the distance of the 
center of gravity from the fulcrum ? 

A. If the lever is of uniform cross-section, its 
center of gravity is at its middle point. 

Q. If the lever is tapering ? 

A. See " Roper's Catechism," page 134. 

Q. What determines the proper area of safety 
valves for different sized boilers ? 

A. They should be capable of discharging twice 
as much steam as corresponds with their rate of 
horse-power. There are many rules given — some 
basing it upon the heating surface, others upon the 
grate surface, and still others upon the coal con- 
sumption. 

Q. Is one safety valve sufficient for a boiler ? 

A. No; it should have at least two. 

Q. What do you mean by a gauge ? 

A. Any instrument or device used for measure- 
ment. 

Q. What are the principal gauges used in con- 
nection with boilers ? 

A. The pressure gauge, vacuum gauge, water 
gauge, and salinometer gauge. 



52 QUESTIONS AND ANSWERS FOR 

Q. What two kinds of steam gauges are there ? 

A. Indicating gauges and recording gauges. 

Q. What is the general principle on which the 
indicating gauge is constructed ? 

A. It is usually constructed on the principle 
invented by Bourdon, and consists of a thin tube 
of elliptical cross-section bent in the form of a 
curve. The steam, the pressure of which is to be 
measured, is admitted into the tube, and its pres- 
sure tends to make the cross-section circular, 
which causes the tube to straighten itself par- 
tially. The tube is so connected with a pointer 
by gearing that the straightening moves the pointer 
over a suitable dial that indicates the pressure. 

Q. How does the recording gauge usually differ 
from this? 

A. It has in addition a clock that moves the 
dial, giving it one revolution in 24 hours, and the 
pointer has a pen or stylus attached that makes a 
complete record of the pressure during this time. 

Q. Does the steam gauge register absolute pres- 
sure? 

A. No; as usually constructed, it stands at zero 
under atmospheric pressure ; therefore its pointer 
indicates the pressure above the atmosphere, or 
about 15 pounds less than absolute pressure. 

Q. Suppose the pointer does not stand exactly 
at zero when there is no pressure in the boiler ? 



STEAM ENGINEERS AND ELECTRICIANS. 53 

A. It should be adjusted by comparison with a 
standard gauge. 

Q. How does a vacuum gauge differ from a 
pressure gauge ? 

A. It is made in the same way, but made to 
read pressure below the atmosphere instead of 
above. 

Q. How are vacuum gauges generally marked ? 

A. So as to read in inches of mercury instead 
of pounds ; that is to say, the readings indicate to 
how many inches the vacuum would allow a col- 
umn of mercury to rise under atmospheric pres- 
sure. 

Q, To what vacuum does an inch of mercury 
usually correspond ? 

A. To a vacuum of about one-half pound. 

Q. Why are the vacuum gauges marked in this 
way and not in absolute pressure ? 

A. Because the mechanism that operates the 
gauge acts by virtue of the difference in pressure 
of the atmosphere and the vacuum chamber ; 
therefore, as the atmospheric pressure is contin- 
ually varying, the pointer would not give accu- 
rately the number of pounds of absolute pressure. 

Q. What is a water gauge, and how is it usually 
arranged ? 

A. It is a device for showing the level at which 
the water stands in the boiler, and usually con- 



54 QUESTIONS AND ANSWERS FOR 

sists of a glass tube placed on the outside of the 
boiler with its upper end connected to the steam 
space and its lower end connected to the water 
space. 

Q. What other devices are used for indicating 
water level? 

A. Gauge cocks and safety water columns. 

Q. What is a salinometer ? 

A. An instrument or gauge for indicating the 
amount of salt contained in the water used in 
marine boilers. 

Q. What is the effect of too great a supply of 
air in the furnace of a boiler ? 

A. It diminishes the economy of the boiler, 
because a portion of the heat of combustion is 
used in heating the excess of air and this amount 
of heat is wasted. 

Q. What are the three common methods of 
operating pumps ? 

A. By belting or gearing, by direct connection 
with a steam cylinder, and by electric motors. 

Q. Which of these methods is usually em- 
ployed for boiler-feed water pumps ? 

A. The second. 

Q. What is a fly-wheel pump ? 

A. One in which the reciprocating motion o\ 
the steam piston is first converted into rotary 
motion by means of the crank shaft, with a fly- 



STEAM ENGINEERS AND ELECTRICIANS. 55 

wheel to help it over dead centers, and then con- 
verted back into reciprocating motion for the 
water cylinder by another crank and rods. 

Q. What is a direct-acting pump ? 

A. One in which the water piston is mounted 
on the same rod as the steam piston. 

Q. What is required in order to help such a 
pump over the dead centers ? 

A. An auxiliary valve gear in addition to the 
main valve gear. 

Q. What is a duplex pump ? 

A. A duplex pump is a combination of two 
pumps coupled together so that the steam valve 
of one is operated by the piston of the other, and 
vice versa. 

Q. What type of steam pump is most com- 
monly used as a boiler-feed pump, and why-? 

A. The duplex pump, because it is the simplest 
form. 

Q. What is the limit beyond which a suction 
pump will not lift water ? 

A. About 33 feet. 

Q. What is the reason for this ? 

A. Because the pump does not actually lift the 
water but only creates a vacuum, allowing the 
water to be lifted by the pressure of the atmos- 
phere on its surface. As the atmospheric pressure 
will not support the column of water more than 



56 QUESTIONS AXD ANSWERS FOR 

33 feet in height, this is the limit to the lifting of 
the suction pump. 

Q. Is there no limit to the distance to which 
water can be thrown horizontally ? 

A. Practically none if the connections are tight. 

Q. What limits the height to which a pump will 
force water? 

A. Nothing except the power of the pump. 

Q. How would you calculate the power required 
to pump water? 

A. Multiply the number of pounds to be 
pumped per minute by the vertical distance in 
feet between the level of supply and discharge, 
and divide the product by 33,000. This result 
will be the theoretical horse-power. The actual 
horse-power will be obtained by adding the losses 
in friction corresponding to the velocity of the 
water. (See "Roper's Handy-Book," page 142.) 

Q. Explain how you would choose the proper 
size of boiler-feed pump for a given boiler. 

A. I would multiply the horse-power of the 
boiler by 30, which would give the number of 
pounds of water that it will evaporate per hour. " 
I would divide this by 8.35, which gives the 
number of gallons; I would then choose a pump 
capable of supplying double this quantity, so that 
it would be large enough even when the boiler 
was being forced to its utmost. 



STEAM ENGINEERS AND ELECTRICIANS. 57 

Q. When the water is hot, what precaution 
must be taken with the pump ? 

A. It should be brass lined, so as not to corrode, 
and must be placed below the level of the water 
supply, as otherwise the hot water will not follow 
the plunger. A valve should also be placed be- 
tween the supply and the pump, so that any 
accumulated vapor may be liberated. 

Q. What is an injector? 

A. An apparatus which forces water against a 
pressure by the direct action of a steam jet upon 
the mass of water. 

Q. Give a description of an injector and how it 
acts. 

A. There is, first, a steam nozzle through which 
the steam enters ; second, a water-supply tube 
through which the water enters; third, a combin- 
ing tube, beginning at the end of the steam nozzle 
where the steam and water come in contact; fourth, 
a delivery tube, from which the mixture of steam 
and water enters the discharge pipe. The action 
of the apparatus is as follows : The steam leaves 
the nozzle and enters the combining tube at a high 
velocity; owing to the friction between the steam 
jet and the air in the water-supply pipe, the air is 
exhausted from the latter, and water consequently 
rises owing to the pressure of the atmosphere on 
its surface. It enters the combining tube where 



58 QUESTIONS AND ANSWERS FOR 

it meets the steam jet and condenses it. By con- 
densation the cross-section of the steam jet is made 
very small, and the entire energy due to its ve- 
locity is thus concentrated upon a very thin jet. 
This amount of energy is more than sufficient to 
force the steam into the boiler, and some of it 
is imparted to the water it meets in the com- 
bining tube, and the entire mixture of steam and 
water is carried into the delivery tube and then 
into the boiler by the acquired momentum. 

Q. What advantages have injectors over pumps ? 

A. The water enters the boiler in a steady 
stream, and practically none of the energy of the 
steam used to operate it is wasted and the water 
enters the boiler hot; they are also more compact 
and have no moving parts. 

Q. Is the injector more economical than a pump 
as a boiler feeder ? 

A. Not always; if the feed water used is cold, 
the injector is more economical, but in combina- 
tion with a feed-water heater a pump is more 
economical. 

Q. Is it desirable that a boiler plant should have 
both a pump and injector ? 

A. Yes; in case one or the other should get out 
of order. 

Q. What is the advantage of heating feed water 
before it enters the boiler ? 



STEAM ENGINEERS AND ELECTRICIANS. 59 

A. It increases the durability of the boiler by 
doing away with the strains that would be pro- 
duced by the entrance of cold water. It prevents, 
to a large extent, the formation of scale by causing 
the deposition of scale-producing impurities in the 
heater instead of in the boiler; it produces a 
marked economy in the consumption of fuel by 
utilizing a portion of the heat in the exhaust 
steam that would otherwise be wasted. 

Q. How much of a saving in the fuel con- 
sumption might be expected from the use of feed- 
water heaters? 

A. About 15 per cent. 

Q. To how high a temperature can the feed 
water be raised by a good heater? 

A. There is no trouble in raising the tempera- 
ture of feed water to 212° Fahr. 

Q. What is the difference between open and 
closed feed- water heaters ? 

A. In the closed type of heaters the exhaust 
steam is not brought in contact with the water to 
be heated, but is carried through a series of brass 
tubes surrounded by the feed water; or the re- 
verse arrangement may be used, the water being 
carried through the tubes and the steam passing 
around them. In open feed-water heaters the 
steam mixes with the water, the latter usually 
passing over a series of steel or iron pans placed 



60 QUESTIONS AND ANSWERS FOR 

in a chamber through which the exhaust steam 
flows. 

Q. How is the pump placed in relation to the 
heater and boiler with open heaters ? 

A. The pump is placed between the heater and 
the boiler, and since it takes hot water, it must 
therefore be placed below the level of the water in 
the heater. 

Q. What is the arrangement with closed heaters ? 

A. With closed heaters the water enters the 
pump cold and is forced through the heater into 
the boiler. 

Q. Can an injector be used with an open heater ? 

A. No; because the water would be raised to 
such a high temperature by the heater that the 
injector will not work, since the injector requires 
moderately cold water in order to condense the 
steam in the combining tube. 

Q. State what you consider to be the relative 
advantages of the two types. 

A. The closed heater must be located in any 
convenient place, while the open heater must be 
placed higher than the pump that is to pump hot 
water. On the one hand, the open type not being 
under the strong steam pressure is lighter and 
cheaper; it is more easily cleaned; heats the water 
to a higher temperature; purifies it better and 
produces no back pressure on the engine ; on the 



STEAM ENGINEERS AND ELECTRICIANS. 61 

other hand, the oil from the cylinder exhaust is 
mixed with the feed water, and unless this is 
eliminated by a suitable oil separator this will 
injure the boiler. 

Q. What is an economizer, and how is it usually 
constructed ? 

A, It is a device for heating the feed water by 
making use of the products of combustion after 
they leave the boiler and before they pass into the 
stack. It is usually made somewhat like a water- 
tube boiler out of a series of tubes connected 
at each end by headers. The water circulates 
through the tubes and the products of combus- 
tion pass around the tube and out into the stack. 

Q. What fittings should an economizer have ? 

A. Like a water-tube boiler, it should have a 
blow-off pipe and a safety valve. 

Q. In what cases are economizers generally used ? 

A. They are generally added to existing boiler 
plants, so as to increase their efficiency. 

Q. Are they generally desirable in new installa- 
tions ? 

A. Not if the boilers are properly designed. 

Q. Can you name other methods of heating 
feed water than by injectors, feed- water heaters, 
and economizers ? 

A. It is sometimes heated by the use of con- 
densers. 



62 QUESTIONS AND ANSWERS FOR 

Q. Will the same rule that you use for calculat- 
ing the boiler shells apply to the calculating of the 
strength of boiler flues ? 

A. No; because the effect of a given pressure 
exerted on the interior of the cylinder is not the 
same as if it were exerted on the outside surface. 
Pressure exerted within a cylindrical tube tends 
to make the tube assume a true cylindrical form ; 
pressure exerted on the outside of the tube tends 
to crush the tube or flatten it. It is well known 
that iron formed into a tube would require a much 
greater force to tear it asunder than would be 
necessary to crush it. 

Q. Does internal pressure cause a tearing strain 
or a crushing strain ? 

A. A tearing strain. 

Q. What is a collapse ? 

A. It is the crushing or flattening of a flue by 
overpressure. 
/ Q. How may long flues be strengthened ? 

A. In various ways: An early method was to 
rivet rings of angle- or tee-iron around the flue at 
fixed intervals ; another method was to make the 
flue in sections and join these sections together by 
riveting on U-shaped .rings ; the more modern 
method is to make the entire flue of corrugated iron. 

Q. What is the advantage of corrugating the 
iron of boiler flues ? 



STEAM ENGINEERS AND ELECTRICIANS. 63 

A. It adds strength, facilitates expansion, and 
increases the heating surface. 

Q. What method of strengthening the flues is 
employed in Galloway boilers ? 

A. Galloway tubes, conical in form, are placed 
within and across the flues and riveted to the sides. 

Q. What relation exists between the length of a 
cylindrical tube and the pressure which will cause 
it to collapse ? 

A. The collapsing pressure is inversely propor- 
tioned to the length of the tube ; that is, with a 
tube of double length the pressure necessary to 
cause collapse is only one-half. 

Q. Describe the simplest form of grate. 

A. A grate consists of a number of cast-iron 
bars shaped like beams, which are supported at 
each end; these bars are placed at a little distance 
apart, so as to allow space between them for the 
passage of air, the distance being from about f to 
-f of an inch ; the grate is placed from 2 to 2^- 
feet above the bottom of the ashpit, and is inclined 
downward toward the bridge wall so that the fuel 
can be more easily distributed. The length of the 
grate is about 6 feet, and its width varies with the 
size of the boiler. 

Q. Is there any fixed relation between the 
amount of coal consumed and the number of 
square feet of grate surface ? 



64 QUESTIONS AND ANSWERS FOR 

A. No; this depends entirely upon the kind of 
draft and the quality of coal; the consumption 
may be as low as 4 pounds, and in locomotive 
boilers with an exceedingly strong draft may run 
as high as 100 pounds. 

Q. What would you consider a fair average for 
stationary boilers using anthracite coal of good 
quality ? 

A. I should consider 9 pounds per square foot 
per hour a fair average. 

Q. Is there any rule between the grate surface 
and the horse-power ? 

A. In stationary boilers about J of a square 
foot per horse-power is allowed, although often 
with particular varieties of coal better results may 
be obtained by changing the area of the grate and 
the amount of draft. 

Q. What is a shaking grate, and what are its 
advantages ? 

A. It is a grate that is operated mechanically 
in such a way that it cleans the fires, breaks up 
clinkers, and removes the ashes, without the 
necessity of opening the fire door. As to its 
advantages, anything which does away with open- 
ing the fire door is desirable, since when it is open 
cold air rushes in and injures the efficiency of the 
boiler and also its durability. The shaking grate 
is also advantageous, in that it prevents the forma- 



STEAM ENGINEERS AND ELECTRICIANS. 65 

tion of clinkers and cleans every part of the grate, 
which it is impossible for the fireman to do with 
the slicing bar. 

Q. Why does the introduction of cold air 
through the fire door diminish the durability of 
the boiler ? 

A. Because the cold air striking against the 
heated boiler plates sets up unequal strains that 
tend to cause leakage. 

Q. What is an automatic stoker ? 

A. An apparatus for feeding coal into, and re- 
moving ashes from, a furnace automatically with- 
out opening the furnace doors. 

Q. What are the advantages to be claimed for 
mechanical or automatic stokers ? 

A. Economy of fuel and labor and prevention 
of smoke. 

Q. Why should stokers be productive of econ- 
omy in the use of fuel? 

A. Because by them the coal is spread upon the 
grate uniformly and in small quantities, whereas 
with hand firing coal is fed at irregular intervals, 
and more is put on than would be necessary to 
get the best combustion; moreover, with mechani- 
cal stokers the furnace doors need not be opened. 

Q. Why do stokers lessen the smoke pro- 
duction ? 

A. For practically the same reasons; the com- 
5 



66 QUESTIONS AND ANSWERS FOR 

bustion being more complete than with the hand 
firing, less smoke is produced. 

Q. AVould mechanical stokers pay in small 
plants ? 

A. No; because their additional cost and the 
power consumed in operating them would more 
than offset the saving they would produce. 

Q. For what is a chimney or stack used ? 

A. To produce a draught that will take away 
from the furnace the products of combustion and 
will draw in fresh air for keeping up combustion. 

Q. Why does a chimney produce a draught ? 

A. Because heated gases being less dense, the 
tendency of the products of combustion is to rise, 
and this produces a partial vacuum that is rilled 
by the rushing of air through the furnace. 

Q. On what does the amount of draught pro- 
duced by a chimney depend ? 

A. On the height of the chimney and the dif- 
ference in weight of the gases in the chimney and 
atmosphere. 

Q. On what does this difference in weight de- 
pend ? 

A. Upon the temperature at which the gases 
leave the boiler. 

Q. At what temperature do gases usually leave 
the boiler ? 

A. From 500° to 600° Fahr. 



STEAM ENGINEERS AND ELECTRICIANS tW 

', Q. On what does the area of the chimney for a 
given boiler depend ? 

A. Upon the quantity of coal to be consumed. 

Q. What is the relation between the quantity 
of coal consumed per hour and the area of the 
chimney ? 

A. The area of the chimney in square inches 
should be about double the number of pounds of 
coal to be consumed per hour. 

Q. What would be the proper area of a chimney 
for a 500 horse-power boiler of the water-tube 
type? 

A. Assuming that 3 pounds of coal are used per 
hour for each horse-power, the total consumption 
of coal per hour would be 1500 pounds. The area 
of chimney should then be about 3000 square 
inches and its diameter about 60 inches. 

Q. What determines the proper height for the 
chimney ? 

A. The strength of draught that is necessary for 
the kind of coal to be burned. Heights of chim- 
neys based upon practical experience are given in 
tables in " Roper's Engineers' Handy-Book." 

Q. What is a steam separator ? 

A. An arrangement for removing moisture from 
steam before it enters the engine cylinder. 

Q. Why is their use desirable ? 

A. Because an accumulation of water in the 



65 QUESTIONS AND ANSWERS FOR 

cylinder from priming or any other cause often 
results in blowing out the cylinder head or steam- 
chest cover. Also, the presence of moisture in 
steam diminishes the economy in the engine. 

Q. What is the general principle on which 
steam separators are constructed ? 

A. Steam enters the apparatus at a high velocity, 
and has its direction of flow altered or reversed so 
as to destroy the momentum of the particles of 
water in the steam. Gravity then causes these 
particles to fall into a passage that is provided for 
the purpose of receiving them. The steam freed 
from the water particles continues into the pipe 
leading to the engine. 

Q. For what other purposes are separators often 
used? 

A. To extract the oil from feed water in open 
heaters. 

Q. What is a steam trap ? 

A. An apparatus for removing condensed steam 
from steam piping without allowing any live steam 
to escape. 

Q. Explain the principle on which some form 
of trap works ? 

A. The trap consists of a closed vessel having 
an outlet that is controlled by a valve; this valve 
is operated by a float, and when sufficient water 
has condensed in the vessel to raise the float the 



STEAM ENGINEERS AND ELECTRICIANS. 69 

valve is opened and a part of the water is drained 
orf and the valve then closes. In another type 
the valve is operated by a bent tube of elliptical 
cross-section similar to that which is used in the 
Bourdon steam gauge; opening and closing of the 
valves are produced by changes in the temperature 
of the elliptical tube; these changes of temperature, 
of course, being caused by the condensation of 
steam. 

Q. Is it necessary to shut down a plant in order 
to clean a separator or trap ? 

A. Not if . the plant is properly piped, as each 
of these pieces of apparatus should be provided 
with auxiliary pipes and valves, so that steam or 
water may be made to pass temporarily around 
them. 

Q. What are these auxiliary pipes and valves 
usually called ? 

A. By-passes. 

Q. Give a brief description, illustrating it by a 
diagram, of one way in which a by-pass is usually 
arranged. 

A. For answer, see "Koper's Catechism," page 
172. 

Q. Why is it always desirable to open, slowly, 
the valves that start an engine ? 

A. It diminishes the strain that would be 
thrown on the boiler, as the sudden vent which 



70 QUESTIONS AND ANSWERS FOR 

would be given to the steam is liable to produce 
strains on the boiler or to cause fluctuations of 
the water level. The strains that would otherwise 
be thrown on the engine are also avoided. 

Q. In shutting down an engine, is slowness in 
closing the valve also desirable ? 

A. Yes; a sudden closing of the valve throws a 
pressure on the valve itself and on the pipe, and 
also on the boiler by suddenly checking the flow 
of steam. 

Q. Is the use of braces in a boiler necessary ? 

A. It would be possible to construct boilers 
strong enough without the use of braces ; such 
boilers, however, would necessarily have exceed- 
ingly thick plates and the riveting would be extra 
heavy, so that the first cost of the boiler would be 
excessive; moreover, such a boiler would not be 
satisfactory, as owing to the thickness of the plates 
they would be liable to burn out quickly. The 
economy of the boiler would also be poor. 

Q. For what purposes are angle braces usually 
employed ? 

A. For bracing the tube sheets of boilers in the 
steam space. 

Q. How are toggle braces usually fastened ? 

A. They are usually riveted in at both ends or 
attached to the shell by lugs; they may be ad- 
justed by means of a swivel or turnbuckle. 



STEAM ENGINEERS AND ELECTRICIANS. 71 

Q. How would you calculate the quantity of 
water which a boiler will hold ? 

A. If the boiler is cylindrical, I would multiply 
the area of the head in square inches by the 
length of the shell in inches and divide by 1728 ; 
this will give the number of cubic feet of the 
water. If there are any tubes or flues, I would 
find their volume similarly and subtract the sum 
of the volumes of the tubes and flues from the 
total contents of the shell. The remainder when 
multiplied b}^ 7J will give the contents of the 
boiler in U. S. gallons. 

Q. What is the difference between a hard and 
soft patch ? 

A. A hard patch is made by taking a piece of 
plate and attaching it at the desired place by 
means of rivets and calking it in the usual man- 
ner. In a soft patch, a coating of lead or litharge 
is applied between the two surfaces and the patch 
is attached with bolts and nuts. 

Q. Which is the better method of patching, 
and why ? 

A. The hard patch, because in soft patching the 
bolt holes being larger than the bolts the patch 
may be moved ; moreover, the packing is not 
positively secure, and though the joint may be 
steam- and water-tight for a time, it is a point of 
danger. 



72 QUESTIONS AND ANSWERS FOR 

Q. Suppose the glass water gauge should break, 
discharging hot water and steam into the room, 
what would you do ? 

A. I would cover one hand with a hat, cap, or 
other flexible covering and with the other hand 
would hold a coat or any piece of cloth in front 
of my face, and would then shut the water valve 
and afterward the steam valve. I would run the 
rest of the day by the gauge cocks, putting in a 
new glass water gauge as soon as possible. 

Q. Suppose that a gauge cock became broken 
off near the boiler, what would you do ? 

A. I would plug up the hole with a piece of 
wood and use the other gauge cocks, putting in a 
new one as soon as possible. 

Q. When a boiler is foaming, can you tell with 
certainty from the gauge glass or from the gauge 
cocks how much water it contains ? 

A. No. 

Q. What would be the best way to find this ? 

A. I would shut down the engine, throw some 
fresh coal on the fire, shut the damper off, and 
open the door ; the foaming will then quiet down, 
and the gauge glass and cocks will give nearly 
correct indications. 

Q. What is the power of a steam engine ? 

A. The amount of work it will do in a certain 
space of time. 



STEAM ENGINEERS AND ELECTRICIANS. (6 

Q. What unit of power is used for steam 
engines ? 

A. The horse-power. 
& Q. What is an engine of one horse-power ? 

A. An engine that will do 33,000 foot-pounds 
per minute; that is, it will raise a weight of 
33,000 pounds one foot per minute, or 550 pounds 
one foot per second. 

Q. If a certain engine raised a weight of 66,000 
pounds in half a minute, what would be its horse- 
power ? 

A. Four, 

Q. What factors determine the horse-power of 
a steam engine? 

A. Length of stroke, diameter of the cylinder, 
speed, and the mean effective pressure on the 
piston. 

Q. Give the rule for calculating the horse- 
power of an engine. 

A. Multiply the area of the piston in square 
inches by the mean effective pressure (in pounds 
per square inch); multiply the length of stroke 
in feet by the number of strokes (twice the num- 
ber of revolutions) per minute; multipty the first 
product by the second and divide by 33,000. 

Q. What would be the horse-power of an 18" x 
18" engine at 100 revolutions per minute, with a 
mean effective pressure of 45 pounds ? 



74 QUESTIONS AND ANSWERS FOR 

A. 104 horse-power. 

Q. What is a convenient formula to remember 
for calculating the horse-power ? 

A. Horse-power equals QQ nAA , in which 

P = mean effective pressure in pounds 

per square inch, 
L = length of stroke in feet, 
A = area* of piston in square inches, 
JV = number of strokes per minute. 
Q. Having given the diameter of the cylinder, 
how would you calculate the area ? 

A. I would square the diameter and multiply 
by .7854, or if I had access to proper tables I 
could find the area from these. 

Q. Explain what you mean by mean effective 
pressure. 

A. Mean effective pressure is the average for- 
ward pressure on the piston less the back pressure. 
Q. Upon what does the average forward 1 pressure 
dej)end ? 

i/ A. It depends upon the initial pressure in the 
cylinder and the point of cut-off. 

Q. How could you find the average forward 
pressure in any engine ? 

A. By taking an indicator card of the engine, 
drawing several vertical lines at equal distances 
from each other on the card, measuring the pres- 



STEAM ENGINEERS AND ELECTRICIANS. t& 

sure on each of these lines and taking the average 
of these pressures. 

Q. Suppose that you had no indicator and 
desired to know approximately the average for- 
ward pressure ? 

A. If I knew the point of cut-off and had 
access to tables such as are found in ' ' Roper' s 
Engineers' Handy-Book," I could find in these 
tables multipliers corresponding to the point of 
cut-off which, if multiplied by the boiler pressure 
(absolute), would give the average forward pres- 
sure. 

Q. What do you mean in your answer by ab- 
solute pressure ? 

A. The pressure above a vacuum. 

Q. Is this the same as the pressure indicated by 
the gauge ? 

A. No; it is about 15 pounds more than the 
pressure indicated by the gauge. 

Q. How would you find the mean effective 
pressure on the piston ? 

A. I would find out, as above, the absolute 
average forward pressure and deduct from this the 
absolute back pressure. 

Q. What is the back pressure ? 

A. It is the pressure opposing the motion of 
the piston; in the case of engines that exhaust into 
the air it is about 15 pounds per square inch. 



76 QUESTIONS AND ANSWERS FOR 

Q. What is the effect of back pressure on an 
engine ? 

A. It diminishes its power. 
Q. What are used with engines to diminish the 
back pressure ? 
A. Condensers. 

Q. Given the following conditions, could you 
calculate the horse-power of an engine ? 
Stroke, 12 inches; 
Diameter, 12 inches; 
Boiler pressure gauge, 80 pounds; 
Speed counter, 300 revolutions per minute; 
Back pressure gauge, 5 pounds; 
Cut-off, J. 
A. I should also need to have an indicator 
card or the multiplier that corresponds to a cut-off 
of J. 

Q. If this multiplier is .5965, explain how you 
would work out the horse-power. 

A. The absolute initial pressure is 80 plus 14.7, 
or 94.7 pounds; multiplying this by .5965 I have 
56.45 as the average forward pressure. The back 
pressure is 5 plus 14. 7, or 19. 7. The mean effective 
pressure, therefore, is 56.45 minus 19.7, or 36.75 
pounds per square inch. The area of piston is 
12 X 12 X .7854, or 113.1 square inches. Thefor- 

P LAN 

inula being H. P. = co ^^ , I should have sub- 
oo,UUU 



STEAM ENGINEERS AND ELECTRICIANS. 77 

stituting figures, H. P. == 36.75 X 1 X 113.1 
X 600 -v- by 33,000, or 75 horse-power. 

Q. What would have been the gain in mean 
effective pressure, supposing that the above engine 
had been used with a condenser in which there 
was a vacuum of 22 inches ? 

A. Since each inch of vacuum corresponds to 
about J pound, the back pressure would have been 
about 11 pounds less than the atmospheric pressure, 
and therefore the mean effective pressure would 
have been about 11 pounds greater. 

Q. Is the initial pressure in the cylinder neces- 
sarily the same as the pressure in the boiler ? 

A. No; it is generally less for several reasons : 
There is a loss of pressure in the steam pipes and 
ports due to friction; and, further, a loss by radi- 
ation and condensation. A throttling governor or 
a leaky piston will also lower the pressure in the 
cylinder as compared to the boiler pressure. 

Q. "What is the common value of the steam 
pressure used in the cylinder of a high-pressure 
engine ? 

A. From 80 to 90 pounds. 

Q. Is a pressure of 90 pounds to the square 
inch more economical than a pressure of, say, 
one-half that amount ? 

A. Yes; for with the lower pressure the loss by 
atmospheric pressure is about 15 pounds, or about 



78 QUESTIONS AND ANSWERS FOR 

one-third of the pressure on the piston, whereas 
with high pressure the loss due to atmospheric 
pressure is only about one-sixth. 

Q. Is an engine larger than necessary for the 
work to be done economical in the use of 
coal ? 

A. No; an engine running below the load for 
which it was designed wastes steam. If it has a 
throttling governor, the steam is throttled at light 
loads, which reduces the pressure without doing 
any useful work, and this means a loss in econ- 
omy; if the engine has an automatic cut-off, the 
expansion is increased at light loads, and this also 
diminishes the economy of the engine, because 
there is one point of cut-off that is more econom- 
ical than any other and the engine is rated at this 
point of cut-off. 

Q. Is there any power derived from the gover- 
nor or fly-wheel on an engine ? 

A. None whatever; the governor acts merely to 
keep the speed of the engine constant, having 
much the same function as does a bridle on a 
horse. The fly-wheel gives out only as much 
power as it receives from the engine, serving 
merely to make the revolution more steady and to 
carry the engine past the dead centers. 

Q. Explain the difference between a condensing 
and a non-condensing engine. 



STEAM ENGINEERS AND ELECTRICIANS. /t> 

A. In a non-condensing engine steam after hav- 
ing expanded in the cylinder and done its work 
escapes either into the atmosphere or into a heat- 
ing system; in a condensing engine the steam ex- 
hausts into a condenser where it comes in contact 
with some cooling substance, in consequence of 
which it is condensed and a partial vacuum is 
produced behind the piston. 

Q. What is the object of condensing ? 

A. To do away with the back pressure on the 
piston, and consequently to increase the mean 
effective pressure and the power. 

Q. In what ratio does the addition of a con- 
denser increase the power of an engine? 

A. In the same ratio which the vacuum in a 
condenser bears to the mean effective pressure. 

Q. Suppose the mean effective pressure without 
the condenser was 40 pounds and the condenser 
had an effective vacuum of 26 inches, what would 
be the percentage increase in power owing to the 
use of the condenser ? 

A. Twenty-six inches correspond to 13 pounds. 
The increase in power is therefore ^|, or 32.5 per 
cent. 

Q. Does it require power to operate a con- 
denser ? 

A. Yes; but usually less than is gained by its 
use. 



80 QUESTIONS AND ANSWERS FOR 

Q. Is there gain in economy of fuel as well as 
in power by the use of a condenser ? 

A. Yes; from 20 to 35 per cent, depending 
upon the size and type of engine. 

Q. Why are not all engines used with con- 
densers ? 

A. Because in small engines the saving is not 
enough to pay for the additional first cost and the 
increased labor and attention necessary; also the 
exhaust steam in many cases can be used to ad- 
vantage in heating; the cost of the water for con- 
densing might also, in some places, be greater 
than the saving in fuel. 

Q. Roughly, how much water is required for 
condensing ? 

A. About 25 times as much as passes through 
the engine. 

Q. What is the difference between a simple 
engine and a multiple expansion engine ? 

A. A simple engine is one in which the steam 
is used expansively in only one cylinder ; the 
multiple expansion engine is one in which the 
steam is partially expanded in the first cylinder, 
and then passes into one or more other cylinders 
where it receives a further expansion. 

Q. What are compound, triple expansion, and 
quadruple expansion engines ? 

A. A compound engine is one in which the 



STEAM ENGINEERS AND ELECTRICIANS. 81 

steam expands twice; a triple expansion engine is 
one in which it expands three times; and a quad- 
ruple expansion engine is one in which it expands 
four times. 

Q. What do you understand by the term ' ' com- 
pounding ' ' ? 

A. Using steam expansively in two or more 
cylinders. 

Q. What is the object of compounding en- 
gines ? 

A. To obtain economy in the use of steam. 

Q. What names are given to the different cyl- 
inders of multiple expansion engines? 

A. The one that takes steam direct from the 
boiler is called the high-pressure cylinder; that 
one in which it expands last before passing to the 
atmosphere or condenser is called the low-pressure 
cylinder; if there are any others they are called 
intermediate cylinders. 

Q. What is a receiver ? Why is it necessary ? 

A. A chamber in which steam is stored after it 
leaves one cylinder until it is admitted into the 
next. It is necessary for engines the cranks of 
which are set at different angles. For instance, in 
the two-cylinder engine they would be placed at 
90 degrees apart, and therefore one cylinder would 
not be taking stea.ni during the time that the pre- 
ceding cylinder was exhausting. Therefore a 
6 



82 QUESTIONS AND ANSWERS FOR 

chamber is necessary to store the steam until it is 
wanted. 

Q. What is the object of setting the cranks at 
different angles ? 

A. To secure a more uniform turning force on 
the crank shaft. 

Q. Why does not the fly-wheel accomplish this 
result ? 

A. It does, but if it can be achieved without a 
fly-wheel it is better. Moreover, in marine en- 
gines a fly-wheel cannot be conveniently used. 

Q. Are compound engines commonly operated 
with condensers? 

A. Yes; it is desirable to so operate them. The 
low-pressure cylinders of multiple expansion en- 
gines often have a mean forward pressure of only 
a few pounds, or on light loads may even have a 
negative forward j)ressure which, instead of aiding 
the other cylinders, tends to diminish the power 
of the engine; therefore the use of the condenser 
is in such cases particularly desirable. 

Q. What would you understand by the term 
' ' high-speed engine ' ' ? 

A. One in which the rotative speed or number 
of revolutions per minute was high. 

Q. What advantages do high-speed engines pos- 
sess in comparison with low speed ? 

A. They are less expensive; are more economic 



STEAM ENGINEERS AND ELECTRICIANS. 83 

cal to operate; run more smooth! y; and they are 
especially adapted for driving electric machinery, 
which requires a high speed of rotation and a 
uniform angular velocity. 

Q. Why should a high-speed engine cost less ? 

A. Because the power of an engine depends 
upon the area of piston, stroke, mean pressure, 
and speed, increasing directly in proportion to the 
increase in any one of these factors; therefore, by 
increasing the speed, any one of the other three 
factors may be proportionately cut down. Hence, 
by doubling the speed of an engine it may be 
built very much smaller and consequently more 
cheaply for a given horse-power. 

Q. Why are high-speed engines more economi- 
cal in the use of steam ? 

A. Assuming that the valve motions are equally 
efficient, and other things are equal in the two 
classes of engines, the high piston speed engine 
will be more economical; for one of the principal 
losses is due to initial condensation and evapora- 
tion in the cylinder, and this is proportionately 
less when more steam passes through a given 
cylinder in a given time. Hence the loss from 
this source is less in the high-speed engine than in 
the low-speed engine. 

Q. What is an automatic cut-off engine, and 
how does it differ from a throttling engine ? 



84 QUESTIONS AND ANSWERS FOR 

A. An automatic cut-off engine is one the speed 
of which is kept constant under varying loads by 
a governor that changes the cut-off so that steam 
is admitted longer for heavy loads than for light 
loads. In a throttling engine the time of admis- 
sion remains the same for all loads, and the initial 
pressure is regulated by a governor which opens 
and closes the throttle valve. 

Q. Which is the less economical, and why ? 

A. The throttling engine; for when the pressure 
is reduced by a throttle valve the steam expands 
without doing useful work, and the energy rep- 
resented by this expansion is wasted. 

Q. Under what conditions would it be advisable 
to use throttling; engines ? 

A. When the load is uniform, or nearly so, 
since throttling engines that use a plain slide valve 
are considerably simpler and cheaper to build than 
are automatic cut-off engines. 

Q. What is the difference between single- and 
double-acting engines ? 

A. In single-acting engines steam is admitted 
on one side of the piston only; in double-acting 
engines steam is admitted first on one side of the 
piston and then on the other. 

Q. What are the advantages of each of these 
types ? 

A. The double-acting engine, for the same 



STEAM ENGINEERS AND ELECTRICIANS. 85 

diameter of cylinder, length of stroke, pressure, 
and speed, develops double the power of the single- 
acting engine. The single-acting engines, however, 
may be made much simpler, needing no piston- 
rod, cross-head, or guides. They may be run 
faster than the same size of double-acting engine, 
as the strain always acts in the same direction and 
as they may be readily arranged, so that the 
crank and the moving parts dip in oil at every 
revolution. 

Q. What does the term "valve gear" of an 
engine comprise? 

A. All the mechanism employed in distributing 
steam. 

Q. Of what parts does the simplest form of 
valve gear consist? 

A. Of a plain slide valve and eccentric and the 
necessary rods or links for transmitting the mo- 
tion of the eccentric to the valve. 

Q. Describe a plain slide valve and illustrate it 
by means of a diagram. 

A. The diagram shows the valve in its central 
position where steam is neither being admitted to 
nor exhausted from the cylinder. Vis the valve; 
S S are the steam passages through which the 
steam passes to the cylinder C from the steam 
chest X. The steam chest is always filled with 
live steam when the throttle valve is open. E is 



86 QUESTIONS AND ANSWERS FOR 




STEAM ENGINEERS AND ELECTRICIANS. 87 

the exhaust passage in communication with the 
exhaust pipe which allows the steam to pass into 
the atmosphere or condenser after it has done its 
work in the cylinder. R is the valve rod which 
derives its motion from the eccentric and imparts 
it to the valve. 

Q. Explain the action of the valve. 

A. In the position of the valve shown in the 
diagram, the piston is moving to the left and is 
nearly at the end of its stroke while the valve is 
moving to the right. A little farther on in its 
motion the valve will uncover the steam passage 
on the left and will admit steam behind the piston. 
The admission of steam will continue until on the 
return stroke the valve again covers the steam 
passage. During this period the passage on the 
right will have been uncovered and in communi- 
cation with the exhaust chamber E, thus allowing 
steam to exhaust until this passage is again covered 
by the valve. After this takes place the process 
is reversed, steam is admitted to the right hand 
end of the cylinder and exhausted from the left. 

Q. What are the four important evejats in the 
distribution of steam which occur in every revolu- 
. tion of the engine ? 

A. Admission, cut-off, release, and compression. 
Admission starts when the passage is first un- 
covered and continues up to the point of cut-off, 



55 QUESTIONS AND ANSWERS FOR 

which is the moment at which the passage is again 
covered ; release occurs when the passage is open 
to the exhaust chamber and continues until the 
passage is again closed ; compression takes place 
from the time of closing the exhaust passage and 
lasts until steam is again admitted. 

Q, During what part of the process does expan- 
sion take place ? 

A. Expansion continues from the time of cut- 
off up to release. 

Q. Explain the meaning of the terms lap, lead, 
eccentricity, travel, over-travel, and angular ad- 
vance. 

A. There are two laps, the outside or steam lap 
and the inside or exhaust lap ; when the valve is 
in its central position, outside lap is the distance 
which the outer edge of the valve extends over the 
outer edge of the steam passage ; inside lap is the 
distance which the inner edge of the valve laps 
over the inner edge of the steam passage. Lead 
is the amount of opening in the steam port at the 
moment at which the piston begins its stroke. If 
the piston begins its stroke before the steam pas- 
sage is open the lead is called negative. Eccen- 
tricity or throw of the eccentric is the distance 
from the center of the engine shaft to the center 
of the eccentric. The travel of the valve is the 
total distance which it moves, and is equal to twice 



STEAM ENGINEERS AND ELECTRICIANS. 89 

the throw of the eccentric. Over-travel is the 
distance which the valve travels beyond what is 
necessary to fully uncover the steam passage. 
Angular advance is the angle by which the eccen- 
tric is in advance of the position which would 
bring the valve in its central position with the 
crank on a dead center. 

Q. How would you set the slide valve of an 
engine ? 

A. I would place the crank on a dead center 
and give the valve the necessary amount of lead, 
then I would turn the engine to the other dead 
center and see if the valve has the same amount 
of lead; if so, it is properly set, if not, the valve 
must be adjusted by means of the valve rod and 
nuts so as to make the leads equal. 

Q. How can you find the exact dead center ? 

A. I would place a spirit level on the top or 
bottom of the stub end or connecting rod boxes, 
and I would move the crank up and down a little 
until level was shown. 

Q. What is a link motion and what is its 
purpose ? 

A. A link motion consists of two eccentrics 
and rods, and a slotted link. It is used for revers- 
ing an engine and for varying its points of cut-off. 

Q, Explain how the Stevenson link accom- 
plishes this. 



90 QUESTIONS AND ANSWERS FOR 

A. The two eccentrics are placed on the shaft in 
such a way that if the valve were operated by one 
the engine would move forward, and if by the 
other it would move backward. The link being 
attached to the end of the two eccentric rods 
receives a rocking motion. A movable block to 
which the valve rod is attached is carried in the 
slot of the link. When the block is at the end of 
the link nearest the forward eccentric, the engine 
will move forward; when the block is at the other 
end the engine will be reversed ; as the block is 
moved nearer the intermediate position the travel 
of the valve becomes less and consequently the 
cut-off becomes earlier. When the block is in the 
central position the travel of the valve is not 
enough to uncover the ports, consequently the 
engine remains at rest. 

Q. In the original form of D slide valve, what 
is the cause of the friction between the valve and 
its seat, and how can this be avoided to a great 
extent ? 

A. The friction is caused by the steam pres- 
sure which is on the back of the valve forcing it 
tightly against its seat. This can be avoided to 
a considerable extent by the use of pressure plates 
which relieve the back of the valve from this 
pressure. 

Q. Is there any form of valve which is natu- 



STEAM ENGINEERS AND ELECTRICIANS. 91 

rally balanced, and if so, is there any objection to 
this form? 

A. Yes; the piston valve. The objection to 
this valve is that the seat wears uneven, and they 
are therefore somewhat difficult to keep tight. 
By proper construction the bushings which form 
the seat can be arranged so that they can be easily 
taken out and replaced. 

Q. Next to the slide valve gear, what is the most 
common valve gear used on stationary engines, and 
what are the important differences between it and 
the plain slide valve gear ? 

A. The Corliss. The Corliss gear instead of the 
single valve which admits and exhausts steam has 
four independent valves which are operated by a 
single eccentric and wrist plate: these four valves 
have a partial rotation about an axis; two of 
them are for admission and cut-off and the other 
two being for release and compression. The two 
steam valves are connected to the wrist plate in 
such a way that they can be detached at any 
moment, This is accomplished by a tripping 
mechanism which is controlled by the ball gov- 
ernor. The cut-off is therefore under the direct 
control of the governor, although release and com- 
pression are constant. 

Q. How does a four-valve engine differ from the 
slide valve and Corliss gears ? 



92 QUESTIONS AND ANSWERS FOR 

A. Like the Corliss it has four independent 
valves, but like the plain slide valve their motion 
is positive and they have no releasing mechanism; 
the cut-off is varied by the travel of the valve. 

Q. What relative advantages have the Corliss 
and the four- valve types ? 

A. The Corliss valve gear gives a sharp and 
quick cut-off and wastes very little power in fric- 
tion; as the valves, however, are controlled by a 
spring or dashpot they cannot be run at a high 
speed. The main advantage of the four- valve gear 
is that it can be run at nearly as high speed as a 
single valve machine, while it preserves most of 
the economy of the Corliss gear. 

Q. What advantage have both of these gears 
over the single valve gears ? 

A. A separate passage is provided for admitting 
steam to the cylinder and for exhausting it, 
therefore, the entering steam does not, as in the 
single valve gear, come in contact with compara- 
tively cold walls; consequently there is much less 
loss by condensation, and these two gears are much 
more economical in the use of steam. 

Q. Suppose the slide valve becomes leaky from 
wear, what would you do ? 

A. I would take it out, have its face planed, and 
the seat filed and scraped. 

Q. What is a rotary valve ? 



STEAM ENGINEERS AND ELECTRICIANS. 93 

A. A valve which has a revolving motion. 

Q. What is a semi-rotary valve ? 

A. A valve which has a motion of revolution, 
but which does not make a complete revolution; 
as, for example, the Corliss valve. 

Q. "What is a gridiron valve ? 

A. A valve with several small narrow openings 
in it, and having very much the appearance of the 
kitchen utensil of that name. 

Q. Is the cut-off produced by the link motion 
capable of producing as satisfactory results as the 
automatic cut-off? 

A. No; because in the case of the link varying 
the cut-off also varies the lead. 

Q. What is an eccentric ? 

A. It is a device used to take the place of a 
crank, and consists of a circular disc and sur- 
rounded by a strap which turns freely on it; the 
center of the disc is somewhat off the center of 
the shaft on which the eccentric is mounted. 

Q. What are the chief methods used for gov- 
erning the speed of stationary engines ? 

A. Varying the initial pressure in the cylinder 
to suit the load by means of the centrifugal gov- 
ernor actuating or throttling valve, and varying the 
point of cut-off by means of a governor actuating 
the valve gear. 

Q. Which is the better method, and why ? 



94 QUESTIONS AND ANSWERS FOR 

A. Varying the point of cut-off, because it gives 
closer regulation and greater economy in the use 
of steam. It is also much less liable to cause 
knocking under very light loads. 

Q. In setting the valves of an engine, is there 
any difference in the leads given at the two ends ? 

A. Yes; a little more lead is given at the crank 
end of the cylinder in order to make up for the 
difference in the area of the two sides of the piston 
due to the piston rod, and also to allow for the short- 
ening of the valve motion on that side as wear is 
taken up. 

Q. Suppose that the nuts which hold the valve 
on the stem should work loose, what would you do ? 

A. I would set the engine on the dead center, 
head end, and after taking the steam chest cover 
off would adjust the nuts so that the valve showed 
a little lead at the head end; then I would turn the 
engine to the other center, and if the proper amount 
of lead showed there the valve would be all right; 
if not, I would, by adjusting nuts, give the proper 
amount of lead and then put on the steam chest 
cover. 

Q. Explain in detail how you would set the 
valves on a Corliss engine of the so-called crab- 
claw type. 

A. See that the governor is on the safety-pin 
and take off the hook rod from the wrist plate. 



STEAM ENGINEERS AND ELECTRICIANS. 95 

Adjust the dashpot rods and reach rods so that 
the wrist plate may be turned through its entire 
travel, taking up the steam valves but without 
releasing them ; next, take out the safety-pin, let- 
ting the governor down and again move the wrist 
plate ; in this case the safeties on the releasing 
cams should keep the crabs down so that they will 
not touch the blocks on the bell cranks and will, 
therefore, not open the steam valves. Xext, turn 
the wrist plate into its central position and adjust 
the connections between the plate and the exhaust 
valves so that the edges of the ports and the valves 
correspond; adjust the connections between the 
wrist plate and steam valves so as to give the 
proper amount of lead (about one-quarter inch), 
turn the eccentric until the rocker arm is vertical 
and adjust it so that the wrist plate will be central. 
Xext, adjust the eccentric rod by turning the 
eccentric shaft to a dead center and adjust the 
length of the rod so that the travel mark in this 
direction just corresponds with the center mark ; 
then turn the eccentric to the other dead center 
and see if the other travel mark corresponds with 
the center mark. If so, the rod is properly 
adjusted. Next, put the engine on its head end 
center and turn the eccentric so as to give the 
proper lead and make it fast; then turn the engine 
to the other center, and if you have the same lead 



96 QUESTIONS AND ANSWERS FOR 

the adjustment is correct. Now put the governor 
in its running position, turn the engine over and 
adjust the rods so as to give equal cut-off. 

Q. At what cut-off is the Corliss engine usually 
run? 

A. About one-quarter stroke. 

Q. How late can the cut-off be made ? 

A. Not more than half stroke. 

Q. In case the lead of the valves at the two ends 
were different, what might cause this ? 

A. The eccentric rod might be either too long or 
too short. If it were too long it would show too 
much lead on the crank end, and if too short it 
would show too much lead on the head end. 

Q. How can the point of cut-off be lengthened 
on the Corliss valve gear ? 

A. By lengthening the head end reach rod or 
shortening the crank end rod. 

Q. Does a Corliss require as much compression 
as a high-speed engine of the same size, and why ? 

A. No, because it does not run as fast; therefore, 
the moving parts have not the same amount of 
energy stored in them, and hence do not need so 
much of an air cushion in the cylinder at the end 
of the stroke. 

Q. If you wish to make a Corliss engine do 
more work without increasing the boiler pressure 
or altering the speed, how could you do this ? 



STEAM ENGINEERS AND ELECTRICIANS. 97 

A. Decrease the lap of the steam valve and turn 
the eccentric back proportionately. 

Q. In what ways may a governor be made to 
vary the cut-off? 

A. By a releasing mechanism as with the Corliss 
valve gear, by the action of the ball governor on 
the block of a link, and by a shaft governor. 

Q. Describe a shaft governor and its method of 
action. 

A. In the shaft governor one or more weights 
are placed in the fly-wheel, and the centrifugal force 
of these weights is balanced against one or more 
springs. The weights are attached to pivoted arms, 
and these arms are connected to the eccentric 
actuating the valve gear. The action of the gov- 
ernor is as follows: When the speed increases, the 
centrifugal force on the weights tends to move 
them away from the shaft, and their motion is 
transmitted through pivoted arms so as to alter the 
position of the eccentric, varying either its angular 
advance or both, and in this way shortening the 
cut-off. 

Q. What difference does it make on the distribu- 
tion of steam, whether the cut-off be varied by 
altering the angular advance or by changing the 
throw of the eccentric? 

A. Changing the angular advance increases the 
lead at the same time as it decreases the cut-off. 
7 



yo QUESTIONS AND ANSWERS FOR 

When the throw of the eccentric is changed the 
reverse action takes place. 

Q. What method then should you consider the 
best for varying the cut-off ? 

A. A method in which both the throw of the 
eccentric and angular advances are changed by the 
governor. 

Q. Having given the number of revolutions of 
the ball governor and the diameter of the engine 
pulley, how would you find the diameter of the 
governor shaft pulley ? 

A. I would multiply the diameter of the engine 
pulley by the number of revolutions and would 
divide the product by the number of revolutions 
of the governor. 

Q. Having given the number of revolutions 
which the governor is to make and the diameter 
of the governor shaft pulley, how would you 
calculate the proper diameter of the pulley to be 
placed on the engine shaft to operate the gov- 
ernor ? 

A. I would multiply the number of revolutions 
of the governor by the diameter of its pulley and 
divide the product by the number of revolutions 
of the engine. 

Q. What do you consider the best material for 
the foundation of machines ? 

A. Hard-burned brick laid in Portland cement. 



STEAM ENGINEERS AND ELECTRICIANS. 99 

Q. Cannot satisfactory foundations be made of 
concrete ? 

A. Yes; if the work is carefully done the 
foundation will be quite as good, but I believe 
that there is a greater risk of careless work in the 
concrete foundations than in the brick. 

Q. What determines the proper depth for foun- 
dations ? 

A. The size of the engine and character of the 
ground. They should always be carried deep 
enough so as to rest on solid ground. If the 
ground at the surface is sufficiently solid, no greater 
depth need be used than would give sufficient 
weight for the foundation to hold the engine down 
and to take up the vibrations of the engine. 

Q. How would you proceed to start an engine ? 

A. I would first see that all the drips were open; 
I would then slightly open the throttle valve and 
warm the cylinder up gradually; then I would 
open the valve still further and start the engine 
slowly, gradually bringing the engine up to speed; 
and after it becomes thoroughly warmed up I 
would close the drips. 

Q. Suppose you had a Corliss engine and the 
main valve on the engine was broken, how could 
you stop the engine ? 

A. I would throw the eccentric hook out of 
gear and stop by means of the starting bar. 

tofC. 



100 QUESTIONS AND ANSWERS FOR 

Q. Suppose you discovered that the cylinder 
was worn hollow in the middle, what would you 
do? 

A. I would have it rebored. 

Q. In case the crank or wrist pin should be cut 
or worn oval, how would you proceed ? 

A. I would caliper them and file them round. 

Q. If the shoes in the cross-head guides become 
worn, what would } r ou do ? 

A. I would put liners between the back of the 
shoe and the cross-head, or would replace them 
with a new set of shoes. 

Q. In case the eccentric slipped or turned on 
the shaft so as to stop the engine, what would you 
do? 

A. I would put the engine on the center, take 
off the bonnet of the steam chest and move the 
eccentric round in the direction in which it used 
to run until the valve had the proper lead; I would 
then fasten the eccentric securely in place with the 
seat screw or a key. 

Q. Suppose the eccentric should become worn 
flat at two points, in the direction of push and 
pull, what course would you adopt to remedy 
the difficulty ? 

A. I would file it down to the smallest diameter 
of the worn part. 

Q. For the lubrication of the engine or any 



STEAM ENGINEERS AND ELECTRICIANS. 101 

other piece of machinery, how much oil is it 
advisable to use ? 

A. No more than is absolutely necessary to 
keep the bearings reasonably cool. The use of 
an excessive amount of oil is not only costly but 
increases an accumulation of gum and dirt in the 
bearings. 

Q. Suppose that any bearings of the engine 
should heat, what would you do ? 

A. I would first examine the oil cups to see if 
the bearings were getting the proper amount of oil. 
If they were and the bearings were new, I would 
cool them temporarily by surrounding them with 
ice, or if possible, of course I would stop the 
engine and try to find out what was the cause. If 
the appearance of the bearings were smooth and 
uniform, I would try to loosen them a very little at 
a time ; if this did not remedy the trouble, I 
should consider that the bearings were out of line 
and would reline them. If the bearings are dirty 
from an accumulation of gum, I would clean them 
with strong lye and oil while the engine is in 
motion. A mixture of flour of sulphur and oil is 
often effective in stopping the heating of bearings. 

Q. When an engine is stopped, how should the 
cylinder drips be left ? 

A. They should be left open so as to allow the 
condensed steam to escape. 



102 QUESTIONS AND ANSWERS FOR 

Q. Explain how you would pack a stuffing 
box. 

A. I would first remove all the old packing and 
clean out the box, then cut the new packing to the 
proper length and put it in place, having the joints 
at opposite sides of the box; I would then screw 
up the stuffing box just far enough to stop the 
leakage. If it is screwed up too tight, the power 
of the engine will be diminished and the packing 
will be quickly worn away. The packing should, 
of course, be perfectly free from dust or grit. 

Q. Suppose that a packing in the piston becomes 
loose, what would be the effect ? 

A. Steam would leak past the piston, materially 
cutting down the power of the engine and wasting 
coal. 

Q. How often should a piston be examined ? 

A. Two or three times a year at least, and, of 
course, at any time when it is suspected that the 
packing or rings need looking after. 

Q. What should be done supposing that the 
joints between the rings and the head are corroded ? 

A. They should be ground with emery and oil, 
or if badly corroded, should of course be faced up 
in a lathe. 

Q. What would be the effect of screwing down 
the packing of the spindle of a ball governor too 
tightly? 



STEAM ENGINEERS AND ELECTRICIANS. 103 

A. It would interfere with the free movement of 
the governor and cause the engine to regulate badly. 

Q. Suppose that you heard a creaking noise in 
the cylinder, to what would you suspect this were 
due and what would you do to remedy it ? 

A. I should suspect the presence of moisture in 
the cylinder, and I would open the cylinder drip- 
cocks. 

Q. What are some of the causes of knocking 
in engines, and how would you proceed to remedy 
the various cases ? 

A. Knocking may be due to a great variety of 
causes. One is lost motion in the boxes either of 
the cross-head, crank pin or pillow blocks, or to a 
looseness of the key holding the piston rod in the 
cross-head. To stop it, of course, the lost motion 
should be taken up either by means of the key or 
by riling the edges of the boxes. Knocking may 
be due to the wrist of the cross-head or crank pin 
being worn out of round. In this case the crank 
or wrist pin should be turned up. If the knock- 
ing is caused by the engines being out of line, the 
remedy would be, of course, to line up the engine 
exactly. Often it is caused by the packing around 
the piston rod being too tight. To remedy the 
trouble, take out the old packing and put in new, 
screwing it up no tighter than is necessary to just 
prevent the escape of steam. Sometimes knock- 



104 QUESTIONS AND ANSWERS FOR 

ing is caused by lost motion in the adjustment 
between the valve and the valve rod; in this case 
remove the cover of the steam chest and adjust the 
jam-nuts on the valve rod. If, as is sometimes 
the case, knocking is caused by the crank being 
ahead of the steam, the trouble will be removed by 
moving the eccentric forward so as to give more 
lead to the valve. The knocking may, however, 
be caused by too much lead, in which case the 
eccentric should be moved back. Knocking may 
be caused bj^ the too early closing of the exhaust; 
in this case the exhaust chamber in the valve 
should be enlarged. Sometimes there is too little 
clearance between the piston and the cylinder 
head, in which case the cylinder head should be 
turned off a little on the inside. It has happened 
that too little counter-bore in the cylinder produced 
knocking, because the piston rings wore a shoulder 
at the ends of the cylinder and when the keys or 
packing rings were set out the edges struck these 
shoulders and caused the knock. In this case the 
remedy is to counter-bore the cylinder again. A 
somewhat similar trouble occurs on the ends of " 
the guides ; shoulders are worn in them and 
produce knocking — the remedy in this case, of 
course, is to replane the guides. Knocking is also 
caused by a loose follower plate. In this case the 
trouble is obviated by bringing the bolts up tight. 



STEAM ENGINEERS AND ELECTRICIANS. 105 

Q. ^'hat does a steam-engine indicator do ? 

A. It records the pressure in the steam cylinder 
at every part of the stroke. 

Q. Describe briefly its construction. 

.4. The indicator consists of a small cylinder, 
which contains a piston, the rod of which is 
enclosed in a spiral spring which opposes the 
motion of the piston. The piston rod after pass- 
ing through the top cylinder cover is attached 
by means of a parallel motion to a pencil on the 
end of a long, light lever. This pencil moves in 
a vertical straight line whenever the piston moves. 
Another cylinder with an axis parallel to the first 
carries a paper drum, and this drum is attached 
by means of a cord and a reducing motion to the 
cross-head of the engine, so that the movement of 
the drum is j:>roportional to the movement of the 
cross-head. When the little cylinder of the indi- 
cator is shut off from connection with the main 
steam cylinder by a cock, the pencil when held 
against the drum makes a horizontal line. If 
now the cock be opened, thus admitting to the little 
cylinder of the indicator the same pressure that 
exists in the main cylinder, the pencil will trace a 
figure, every point of which is at a height from the 
horizontal proportional to the number of pounds 
pressure in the main cylinder at that point of the 
stroke. 



106 QUESTIONS AND ANSWERS FOR 

Q. What is the atmospheric line in the indicator 
diagram ? 

A. It is the horizontal line drawn by the pencil 
when the little cylinder of the indicator is open 
to the atmosphere. 

Q. What things about an engine can you ascer- 
tain by taking an indicator diagram ? 

A. First, the forward pressure of the piston and 
the back pressure at every point in the stroke, 
from which can be calculated the average forward 
and average back pressure and the mean effective 
pressure on the piston. Second, the power of the 
engine under all conditions, if in addition to tak- 
ing the indicator diagram we know also the speed. 
Third, the diagram shows when steam is admitted, 
cut off, exhausted, and compressed, and therefore 
shows whether the valves are properly set. 

Q. Explain how you would calculate the mean 
effective pressure from an indicator card, and state 
what you would need to know. 

A. I would need to know the scale of the spring. 
I would draw a vertical line at each end of the 
diagram, then I would draw 20 vertical lines 
parallel to this, dividing the card into equal spaces, 
except the first and last spaces which would be 
one-half size. Then on these verticals I would 
measure the length between the back pressure line 
and the forward pressure line, and mark each 



STEAM ENGINEERS AND ELECTRICIANS. 107 

length on a long strip of paper. The sum of all 
these lengths I would divide by 20, which would 
give the average length of ordinates, and these 
multiplied by the scale of the spring will give 
the mean effective pressure. 

Q. Is the power furnished by the crank end of 
the engine the same as that furnished by the head 
end, assuming that the indicator cards are exactly 
alike ? 

A. No ; while the mean effective pressure would 
be the same the area of the crank end of the 
piston is not all effective since steam does not press 
on that portion of the piston to which the piston 
rod is attached ; therefore, in calculating the power 
of the crank end the area of the piston rod should 
be subtracted from the area of the piston, and the 
difference between the two areas should be used 
in the formula for horse-power. 

Q. For what is a condenser used ? 

A. A condenser is used to condense steam ex- 
hausted from an engine so as to reduce the back 
pressure against which the engine is working. 

Q. What effect has the condenser on the power 
of a given engine ? 

A. It increases the power of the engine from 20 
to 30 per cent. 

Q. What are the principal types of condensers 
used ? 



108 QUESTIONS AND ANSWERS FOR 

A. There are two types — jet condensers and 
surface condensers. 

Q. What is the difference between the two 
types? 

A. In jet condensers the steam to be condensed 
comes in contact in the condenser pump with the 
condensing water; in surface condensers the steam 
and condensing water do not mix, one of them 
being in a series of tubes and the other being in a 
vessel surrounding the tubes. 

Q. What are the advantages of the two types ? 

A. Surface condensers have the advantage for 
use on shipboard, since the condensed steam not 
coming in contact with the salt condensing water 
it may be used again in the boilers. Steam of 
any pressure may be condensed and the vacuum 
is usually higher than in jet condensers ; they are 
much more expensive, however, and are more 
liable to have their vacuum impaired by the leak- 
ing of tubes. 

Q. Can a surface condenser be converted into a 
jet condenser and vice versa f 

A. The surface condenser can be used as a jet 
condenser by admitting the steam and injection 
water into the same chamber; but a jet condenser 
cannot be used, of course, as a surface condenser. 

Q. At what temperature does a jet condenser 
work best? 



STEAM ENGINEERS AND ELECTRICIANS. 109 

A. At about 100° Fahr. 

Q. What vacuum can be obtained in a good 
condenser ? 

A. Up to about 26 inches. 

LESS PRACTICAL QUESTIONS. 

Q. What is power ? What is the unit of power ? 

A. Power is the rate of doing work; that is to 
say, the number of foot-pounds of work done per 
minute. The ordinary unit of power is the horse- 
power, which is a rate of doing work equal to 
33,000 foot-pounds per minute. 

Q. Suppose that a pump raises 66,000 pounds 

of water four feet and the time required for doing 

it is two minutes, what is the horse-power ? 

a ™ , 66,000 X 4 ,_ 

A. Thehorse-power = 33?000><2 = 4 H. P. 

Q. What is the rule for obtaining the horse- 
power in any given case ? 

A. Multiply the number of the pounds raised 
by the number of feet which it is raised, and 
divide by the number of minutes which it takes 
to do the work. Divide further by 33,000 and the 
result is the number of horse-power. 

Q. How could you measure the power required 
by a certain machine if it were driven either 
direct from an engine or from a shaft which 
receives power from an engine ? 



110 QUESTIONS AND ANSWERS FOR 

A. I would indicate the engine with the machine 
running, and calculate the power from the indicator 
card; I would then stop the machine and indicate 
the engine again and calculate the power from the 
card. The difference between the two powers will 
be practically the power required for operating the 
machine. 

Q. Suppose that the machine, instead of being 
driven by an engine, were operated by an electric 
motor, could you measure the power, and if so, 
what instruments would you require and how 
would you proceed ? 

A. Yes; if I had the proper instrument. I 
should need an ammeter and voltmeter of suit- 
able range. I would measure the current with the 
ammeter by connecting it so that the main cur- 
rent passed through the instrument, and I would 
measure the voltage of the motor by connecting 
the voltmeter across the brushes. If the motor 
is a direct current motor the products of the volts 
and the current divided by 746 will give the horse- 
power. 

Q. How would you calculate the weight which 
can be lifted with a lever by the application of a 
certain force at one end of the lever? 

A. Multiply the applied force by the distance 
from its point of application to the fulcrum, and 
divide this product by the distance from the ful- 



STEAM ENGINEERS AND ELECTRICIANS. Ill 

crum to the weight to be lifted. The quotient 
will be the weight which can be lifted. 

Q. What is heat, and how does it differ from 
temperature ? 

A. Heat is a form of energy, while temperature 
is a measure not of the heat in a body, but of the 
tendency of that body to give up its heat to other 
bodies. 

Q. So far as the engineer is concerned, how is 
heat generally produced? 

A. By the combustion of fuel in the furnace of 
the boiler; the combustion being due to a combi- 
nation of the oxygen in the air with the constit- 
uents of the fuel. 

Q. Describe the instrument with which tem- 
perature is measured. 

A. Temperature is measured by means of a ther- 
mometer, which consists in its ordinary form of a 
small hollow glass tube with a bulb at its bottom. 
After the air has been exhausted from the tube it 
is partially filled with mercury and the upper end 
is sealed. Then, either the tube itself is graduated 
or it is placed in a case which has graduations by 
which the height of mercury in the tube can be 
read. Whenever the instrument is heated the 
mercury column rises owing to the expansion of 
mercury in the bulb, but when it is cooled the 
opposite action takes place. 



112 QUESTIONS AND ANSWERS FOR 

Q. How are the graduations made in the ordi- 
nary Fahrenheit thermometers ? 

A. The instrument is placed in melting ice and 
the position of the mercury column marked 32°; it 
is then placed in boiling water at atmospheric 
pressure and the new position of the mercury 
marked 212. The distance between the two marks 
is divided into 180 equal parts called degrees. 

Q. What other thermometers are used besides 
the Fahrenheit ? 

A. The Centigrade and Reaumur. 

Q. What is the difference between the Centi- 
grade and the Fahrenheit scale ? 

A. In the Centigrade the point at which mercury 
stands when the thermometer is placed in melting 
ice is marked zero; and the point for boiling water 
is marked 100. The distance between the two 
parts is divided into 100 equal parts. 

Q. What is the unit of heat? 

A. The unit of heat is the amount of heat 
which will be able to raise the temperature of 1 
pound of water 1 degree. 

Q. What is the ' ' specific heat ' ' of any sub- 
stance ? 

A. It is the number of heat-units necessary to 
raise the temperature of 1 pound of it 1 degree. 

Q. Is there any relation between units of heat 
and units of work ? 



STEAM ENGINEERS AND ELECTRICIANS. 113 

A. One heat-unit equals 778 units of work (foot- 
pound). 

Q. What is latent heat ? 

A. Latent heat is heat absorbed by a body when 
it changes its physical state. For instance, when 
it changes from a solid to a fluid state, as from ice 
to water, the heat absorbed is called the latent 
heat of liquefaction. The heat absorbed in chang- 
ing from water to steam is called the latent heat of 
vaporization. 

Q. In what ways is heat transferred from one 
body to another ? 

A. It is transferred by radiation, conduction, and 
convection. 

Q. In a boiler, how is it transferred from the fire 
to the steam ? 

A. By conduction in the iron, and from the iron 
to the particles of water touching the iron; it is 
then transferred from these particles to the others 
by conduction and convection. 

Q. What substances are in general the best con- 
ductors" of heat? 

A. The metals. 

Q. What kind of substances radiate heat best ? 

A. Substances of dark color with roughened 
surfaces. 

Q. Why are the coverings of steam pipes 
painted white ? 



114 QUESTIONS AND ANSWERS FOR 

A. Because we desire to have as little heat as 
possible radiated from the pipes, and white radiates 
less than dark colors. 

Q. Why should a bare copper pipe carrying 
steam be kept brightly polished ? 

A. Because if allowed to become dull more heat 
would be radiated. 

Q. What are some of the best non-conductors 
of heat? 

A. Magnesia, mineral wool, hair felt, and cork. 

Q. What would be the objection to leaving 
steam pipes bare ? 

A. There would be a waste of fuel caused by 
loss of heat, which is radiated from the pipes; 
there would be a loss of pressure in the steam and 
a condensation of steam into water, which, if 
carried over into the engine, would be liable to give 
trouble. 

Q. How many pounds of air will be required 
to burn a pound of coal ? 

A. About 12 pounds. 

Q. What is the cause of smoke ? 

A. Smoke is caused by imperfect combustion 
of the fuel ; the black appearance being due to the 
presence of small unburned particles hanging 
suspended in the air. 

Q. What are some of the principal fuels used 
in making steam ? 



STEAM ENGINEERS AND ELECTRICIANS. 115 

A. Coal, coke, wood, petroleum, and gas. 

Q. What are the chief constituents of coal ? 

A. Carbon is the chief constituent. Coal also 
contains hydrogen and nitrogen and sulphur, 
together with the constituents forming the ash. 

Q. How many heat-units are produced by the 
complete combustion of one pound of good coal ? 

A. About 13,000. 

Q. What is the difference between anthracite 
and bituminous coal ? 

A. Anthracite is nearly all carbon, while bitumi- 
nous coal has a large percentage of other materials. 

Q. How many pounds of wood (roughly) are 
needed to produce as much heat as a pound of coal ? 

A. About 2\ pounds. 

Q. How great an evaporation per pound of coal 
can be obtained practically ? 

A. About 11 pounds. 

Q. What proportion does the ash bear to the 
amount of fuel ? 

A. The ash will vary anywhere from 1 to 30 
per cent, of the amount of fuel. 

Q. Of what is the atmosphere composed ? 

A. Of a mixture of about one part (by volume) 
of oxygen to four parts nitrogen. 

Q. Does air have weight ? 

A. Yes; a weight per cubic foot varying with 
the pressure. 



116 QUESTIONS AND ANSWERS FOR 

Q. To what is the atmospheric pressure, so- 
called, due? 

A. It is due to the pressure which the air exerts 
on all bodies by virtue of its weight. As the 
atmosphere extends to a distance of some forty- 
five miles from the earth's surface, every square 
inch is subjected to a pressure equal to the weight 
of a column of air one square inch cross-section 
and some forty-five miles long. 

Q. How does the weight per cubic foot compare 
with that of steam at atmospheric pressure ? 

A. The weight of air is about double the weight 
of steam. 

Q. What is the effect of the application of heat 
to air? 

A. It expands the air -^^ °^ ^ s volume for 
each degree rise in temperature. 

Q. How much is the pressure of the atmosphere 
at sea level ? 

A. About 14.7 pounds per square inch. 

Q. What instrument is used to measure atmos- 
pheric pressure ? 

A. The barometer. 

Q. Will the barometer read higher on a moun- 
tain or at the sea level ? 

A. It will read higher at the sea level, because 
the mercury column is forced up by the weight of 
a longer column of air. 



STEAM ENGINEERS AND ELECTRICIANS. 117 

Q. "Will water boil at the same temperature on 
a mountain as at sea level ? 

A. Xo; it boils at a lower temperature on a 
mountain, because the pressure of the atmosphere 
which tends to prevent the steam from rising from 
the surface of the water is less on a mountain than 
at sea level. 

Q. What is the composition of water ? 

A. Water is composed of about eight parts, by 
weight, of oxygen to eleven parts of hydrogen. 

Q. What is the weight per cubic foot of water ? 

A. The weight per cubic foot of moderately 
pure water is about 62.5 pounds. Impurities in 
the water will increase its weight so that sea water 
is much heavier than fresh water. 

Q. In what three physical states or forms does 
water exist? 

A. In the form of ice, water, and steam. 

Q. What is necessary to change from one form 
to the other ? 

A. We can change the physical state of water 
by either applying or withdrawing heat from it. 

Q. At what temperature does water boil ? 

A. This depends upon its purity and the pres- 
sure acting upon it. Pure water at sea level boils 
at 212° Fahr. 

Q. Is the boiling-point of salt water the same 
as that of fresh? 



118 QUESTIONS AND ANSWERS FOR 

A. No; it is higher. 

Q. What is the weight of a cubic foot of ice ? 

A. About 57 pounds. 

Q. How many units of heat are necessary to 
change a pound of ice into water ? 

A. About 142. 

Q. What is the scientific name given to this 
number ? 

A. The latent heat of liquefaction. 

Q. How many heat-units are necessary to con- 
vert a pound of water into steam ? 

A. At atmospheric pressure, about 965. 

Q. How many cubic inches of water are there 
in a gallon ? 

A. In the standard U. S. gallon, 231. 

Q. What would be the pressure per square inch 
produced by a column of water 10 feet high ? 
Explain how you would calculate this. 

A. A cubic foot of water weighs 62. 5 pounds, 
therefore a cubic inch weighs 62.5 divided by 1728. 
A column of water 12 inches high and one square 
inch cross-section would weigh 12 times this 
amount, or .434 pound. Therefore, the pressure 
produced by the column 10 feet high would be . 
.434 times 10, or 4.34 pounds per square inch. 

Q. What is the difference between ' ' hard ' ' and 
"soft" water? 

A. "Hard" water is water that holds mineral 



STEAM ENGINEERS AND ELECTRICIANS. 119 

salts in solution. ' ' Soft ' ' water is water that is 
practically free from impurities. 

Q. What do you understand by the term 
■ ' head ' ' applied to water ? 

A. I understand a difference in level or the 
pressure due to that difference in level. 

Q. What is steam ? 

A. Steam is the gaseous form of water, and is 
produced from water by the action of heat. 

Q. Can you see steam ? 

A. No; steam itself is invisible, being, like air, 
without color. If, however, a jet of steam be 
allowed to flow into the air it will form a cloud; 
this cloud is not the steam itself, but is produced 
by water particles condensed from the steam. 

Q. What is the relative volume of space occu- 
pied by steam and by the water from which it 
is produced? 

A. At atmospheric pressure a cubic inch of 
water when changed into steam will occupy a 
space of about one cubic foot. Of course, if the 
steam is subjected to a greater pressure its volume 
will become proportionately less. 

Q. What is superheated steam? 

A. It is ordinary dry steam, which, after being 
removed from contact with the water from which 
it is produced, is raised by the application of heat 
to a higher temperature. 



120 QUESTIONS AND ANSWERS FOR 

Q. Is there any relation between the pressure of 
steam and its temperature ? 

A. Yes; a certain temperature always corre- 
sponds to a certain pressure. The actual values of 
pressure and temperature are given in steam tables. 

Q. What is the temperature of steam at 60 
pounds gauge pressure; 100 pounds; and 135 
pounds ? 

A. 307°, 337°, and 358°, respectively. 

Q. In the steam tables, what is the meaning of 
latent heat of vaporization ? 

A. The number given in the tables in the 
column under latent heat means the number of 
units of heat which must be applied to a pound of 
water at the corresponding pressure in order to 
change it into steam at that pressure. 

Q. When a pound of steam at a temperature of 
100 pounds gauge pressure condenses, how much 
heat is given off ? 

A. In condensing it gives up a number of heat- 
units equal to the latent heat of steam at that 
pressure. During this process the temperature of 
the steam does not change. 

Q. After all the steam is condensed into water, 
suppose that the water cools to a lower tempera- 
ture, how much heat is given off ? 

A. The number of heat-units given off will be 
equal to the heat of the liquid (or sensible heat) 



STEAM ENGINEERS AND ELECTRICIANS. 121 

at the higher temperature less that at the lower 
temperature. 

Q. What is the weight of a cubic foot of steam ? 

A. This depends entirely upon its pressure. 
At atmospheric pressure the steam from a cubic 
inch of water occupies about one cubic space, so 
that its weight per cubic foot would be about 3-7V5- 
of the weight of water. The weight of the cubic 
foot of water being 62.5 pounds, the weight of a 
cubic foot of steam at atmospheric pressure will 
be found by dividing 62.5 by 1700. 

Q. If you put a thermometer first in the steam 
space of a boiler and next in the water space, will 
its readings be any different in the two places ? 

A. Xo; the temperature of water and of steam 
in contact with it is always the same. 

Q. What is the specific gravity of a substance ? 

A. The ratio of its weight to an equal bulk of 
water. 

Q. What is the difference between cast and 
wrought iron ? 

A. Cast iron is less pure, and contains carbon 
and other impurities. It has a crystalline struc- 
ture and cannot be hammered or drawn out like 
wrought iron. 

Q. What is steel ? 

A. Steel is a modification of iron produced by 
mixing with it a small percentage of carbon; 



122 QUESTIONS AND ANSWERS FOR 

the amount of carbon being determined by the 
special properties which it is desired to produce 
in the steel. 

Q. What is the effect of heat on iron or steel ? 

A. It expands it, and up to a certain point 
(about 600° Fahr. ) increases its strength some- 
what. 

Q. What is brass ? 

A. Brass is an alloy of copper and zinc in 
various proportions. 

Q. What is bronze ? 

A. Bronze is an alloy of copper and tin. 

Q. What do you understand by the term 
' ' tensile strength " of a material ? 

A. I understand the number of pounds of pull 
that must be exerted on a piece with one square 
inch cross-section in order to rupture the piece. 

Q. What do you understand by the term ' ' com- 
pressive strength," and what other expression is 
often used? 

A. The expression " crushing strength " is often 
used. The crushing strength is the number of 
pounds per square inch that must be applied in 
order to crush the material under test. 

Q. What is the tensile strength of cast iron, 
approximately, and what is its crushing strength ? 

A. Tensile strength, about 16,000 pounds per 
square inch; crushing strength, about 100,000. 



STEAM ENGINEERS AND ELECTRICIANS. 123 

Q. What are the tensile and compressive 
strengths of wrought iron ? 

A. They are nearly equal to each other, being 
about 50,000 pounds per square inch. 

Q. What is the strength of steel ? 

A. The strength of steel varies very greatly 
according to its composition. Mild steels low in 
carbon have a strength of about 50,000 pounds. 
Steels high in carbon may have a strength as high 
as 200,000 pounds per square inch. 

STEAM HEATIXG. 
Q. What are the two principal systems of steam 
heating in use at the present day ? 

A. The gravity and the reducing systems. 
Q. What are the distinguishing features of the 
gravity system ? 

A. The boiler is placed below the level of any 
radiator. Steam is generated at a pressure rarely 
exceeding ten pounds and is carried to the radia- 
tors through a supply main and branches. From 
the other end of the radiator a branch connects to 
a return main, which carries the water of con- 
densation back to a low point in the water space 
of the boiler. 

In this system the circulation or return flow of 
water to the boiler is produced by gravity alone. 

Q. What are the advantages of this system ? 



124 QUESTIONS AND ANSWERS FOR 

A. Its chief advantages are its simplicity, ease 
of operation, and cheapness in first cost. It is as 
economical, in fact more so, considered simply 
from the heating standpoint, although when the 
heating system is auxiliary to a power plant the 
reducing system may be cheaper in operation. 

Q. What are the necessary valves in the gravity 
system ? 

A. A stop valve in the riser near the boiler, and 
a stop and check valve in the return pipe, where 
it enters the boilers with the stop valve nearest the 
boiler, and a blow-off valve. 

Q. What other fittings should a boiler have ? 

A. Safety valve, pressure gauge, gauge cocks, 
and water gauge glass. 

Q. In this system, how do we get the extra 
supply of feed- water that will be required on ac- 
count of leakage or waste ? 

A. The boiler is connected to the city mains 
through a valve. 

Q. Is a pump, inspirator, or injector necessary ? 

A. No ; because the pressure used is so low 
that the city pressure is always sufficient to force 
water into the boiler. 

Q. When put in charge of a boiler, what would 
you do in order to find out whether or not it were 
in good working condition ? 

A. Examine the fittings of the boiler and see 



STEAM ENGINEERS AND ELECTRICIANS. 125 

that the stop valves are closed. Turn on city 
pressure (if this pressure is higher than the safe 
working pressure of the boiler, the feed valve 
must be kept sufficiently closed to prevent the 
pressure on the boiler from rising to a dangerous 
point) and notice if the reading of the gauge cor- 
responds with the pressure at which the safety 
valve blows. Open the gauge cocks and let the 
boiler gradually fill. When the water gets high 
enough try the water-gauge cock. Fill the boiler 
completely, closing the cocks and safety valve, 
and turn the city connection until the gauge shows 
a pressure a little less than the blow-off pressure. 
Then examine carefully all accessible parts of the 
boiler to see if there is any leakage. 

Q. Explain what is the proper method of start- 
ing up when the boiler has been out of use and 
contains no water. 

A. Fill the boiler with water to second gauge 
cock and open the steam stop valve. Start a fire 
slowly so that the water and boiler may be heated 
gradually and evenly in order to avoid strains 
from unequal expansion. As soon as the pressure 
gauge shows one or two pounds examine all pipe 
and the radiators for leaks. These being tight 
the steam may be raised to the desired pressure. 

Q. Explain what should be done when a boiler 
is to be shut down for the summer. 



126 QUESTIONS AND ANSWERS FOR 

A. Let the fire go out and allow the boiler to 
cool for several hours, then open the blow-off 
valve and let all water drain from the boiler; at the 
same time allow air to enter the boiler through 
cocks or safety valve. Open all jet- and drip- 
cocks in order to drain any water that may have 
collected in the fittings or connections. Finally, 
clean the boiler of all dirt and ashes. 

Q. What would you do if at any time a serious 
leak should occur in the mains or radiators ? 

A. If the leak were in a radiator I would shut 
it off by closing its two valves. If, however, the 
leak were in the mains or branch connections, I 
would shut off both stop valves and draw the fire. 

Q. What are the important features of the re- 
ducing system of steam heating ? 

A. Steam is generated at a high pressure for 
power purposes. This steam is afterward re- 
duced to a low pressure by passing it through a 
reducing valve. 

The steam condensed in the radiators passes 
through the return pipe into a trap, and from the 
trap to a receiver tank or hot well, from which 
it is forced into the boiler by a pump or injector. 

Q. What is the purpose of the trap ? 

A. To take the water of condensation from the 
pipe without letting any of the steam escape. 

Q. In a system where steam is carried to the 



STEAM ENGINEERS AND ELECTRICIANS. 127 

top of the building and then distributed to the 
radiators through vertical risers, where is it desir- 
able to place an auxiliary trap, and why? 

A. There should be a trap to take the drip 
from the bottom of all the supply risers in order 
to keep these risers free from water of condensa- 
tion, which would impair the circulation of steam. 

Q. What is a reducing valve ? 

A. It is a valve for lowering the pressure of 
steam. 

Q. Describe any forms of reducing valve with 
which you are familiar. 

A. In one variety the valve is of the piston 
type and is pressed upward by the low pressure 
steam and downward by a lever and weight. High 
pressure steam is in an annular chamber surround- 
ing the hollow piston. When the pressure in the 
heating system falls below that for which the 
weight is set the piston is forced downward. This 
movement opens a series of small ports by which 
the live steam passes through the hollow piston and 
out through its open bottom into the heating sys- 
tem. As soon as the pressure on the under side 
is as great as that for which the weight is set the 
piston rises and live steam is shut off. 

Another variety consists of a balanced valve 
having two discs of the same size on the same 
stem. The live steam presses up against one disc 



128 QUESTIONS AND ANSWERS FOR 

and down against the other. As these discs are 
of the same size the live steam has no tendency 
to move the valve. Motion is produced by a 
weight and lever which tend to open the valve, 
and by the action of the low pressure steam on a 
diaphragm, which tends to close it. An adjustable 
spring is sometimes used in place of a weight and 
lever. 

Q. With a reducing valve, how can the pressure 
in the heating system be raised or lowered ? 

A. By moving the weight on the lever or ad- 
justing the tension on the spring. 

Q. What fittings should be placed on the main 
supply pipe of a reducing system ? 

A. A stop or throttle valve, a reducing valve 
and a low reading pressure gauge. 

Q. What openings has the receiver tank ? 

A. One for the entrance of condensed steam 
from the heating system ; one for the entrance of 
city water ; one for emptying the tank ; one for a 
vent to the atmosphere ; finally, one connecting 
with the suction of the boiler feed pump. 

Q. What fittings are often placed on a receiver 
tank? 

A. A water gauge glass, to show the level 
at which the water stands in the tank, and a 
device consisting of a float and lever which opens 
the valve admitting steam to the pump when- 



STEAM ENGINEERS AND ELECTRICIANS. 129 

ever the level of the water in the tank rises above 
a certain height. 

Q. To which system does the ordinary method 
of heating with exhaust steam belong? 

A. To the reducing system. The steam engine 
takes the place of the reducing valve. 

Q. "Why is it necessary to employ an oil sepa- 
rator when exhaust steam is used for heating ? 

A. In order to extract the oil which has been 
taken up by the steam in its passage through the 
cylinder. 

Q. What harm would result in leaving the oil 
in the exhaust steam ? 

A. This oil would accumulate in the pipes and 
boiler. It would leak out of joints in the piping 
and at the seams and tube ends of the boiler. It 
would also produce foaming. 

Q. W T hat is the Webster vacuum system ? 

A. It is a reducing system in which the circula- 
tion is produced by a vacuum pump attached to 
the return pipes. 

Q. W r hat are the advantages of the Webster 
vacuum system? 

A. It diminishes the back pressure on the en- 
gine, and allows the use of a smaller size of pipes; 
different radiators on the same system may be kept 
at different temperatures, and radiators may be 
operated at a level below that of the receiving tank. 



130 QUESTIONS AND ANSWERS FOR 

Q. Describe that method of piping known as 
the single pipe system. 

A. Each radiator has but one outlet and one 
valve. The condensed steam flows back through 
the same branch pipes and risers as carry the 
steam supply, and is collected in a trap, from 
which it is taken to the boiler in the same way as 
in the double pipe system. 

Q. What are the advantages and disadvantages 
of the single pipe system ? 

A. Its chief advantage is its lower first cost. It 
has the disadvantage of a poorer circulation. 



STEAM ENGINEERS AND ELECTRICIANS. 131 



QUESTIONS FOR MARINE ENGINEERS. 

Engineers desiring to enter the Merchant Marine 
are required to pass an examination before the 
Supervising Steam Inspector of their district. 
The name and address of the Inspector can be 
obtained from the Secretary of the Treasury. 

The requirements for engineers are not very 
definitely established by law, as will be seen by 
reading the extract from the rules of the Board of 
Supervising Inspectors. (Seep. 132.) 

In a bill introduced by Senator AVm. P. Frye, 
which embodies the recommendations of the United 
States Delegates to the International Marine Con- 
ference, the requirements of the various grades 
are presented in much greater detail. Although 
this bill was not passed, the recommendations 
therein contained have had an undoubted influ- 
ence, and act as a guide to the supervising steam 
inspectors in determining upon the fitness of 
applicants. 

In the following extracts from the Rules and 
Bill will be found only those sections that apply 
particularly to the qualifications of marine engi- 
neers and to the range of subjects in which they 
must be proficient. 

As the requirements for chief engineer extend 



132 QUESTIONS AND ANSWERS FOR 

beyond the scope of the " Roper's Handy-Books," 
no questions for that grade have been included in 
this book. 

EXTRACT FROM THE RULES AND REGULATIONS 
OF THE BOARD OF SUPERVISING INSPECTORS 
OF STEAM VESSELS. 

1. Before an original license is issued to any 
person to act as a master, mate, pilot, or engineer, 
he must personally appear before some local board 
or a supervising inspector for examination ; but 
upon the renewal of such license, when the dis- 
tance from any local board or supervising in- 
spector is such as to put the person holding the 
same to great inconvenience and expense to appear 
in person, he may, upon taking the oath of office 
before any person authorized to administer oaths, 
and forwarding the same together with the license 
to be renewed, to the local board or supervising 
inspector of the district in which he resides or is 
employed, have the same renewed by the said in- 
spectors if no valid reason to the contrary be 
known to them ; and they shall attach such oath 
to the stub end of the license, which is to be re- 
tained on file in their office; Provided, however, 
That the applicant for renewal is at the time per- 
sonally within the jurisdiction of the United States 
Inspection Laws, as defined in sections 4400 and 
4447 of the Revised Statutes.* And inspectors 
are directed when licenses are completed, to draw 

* Proviso substantially repealed by Act of Congress ap- 
proved May 28, 1896. 



STEAM ENGINEERS AND ELECTRICIANS. 133 

a broad pen and red-ink mark through all unused 
spaces in the body thereof, so as to prevent as far 
as possible illegal interpolation after issue. 

Mates, assistant engineers, or second-class pilots 
serving under five-years' license, entitled by license 
to raise of grade, shall have issued to them new 
licenses for the grade for which they are qualified, 
the local inspectors to forward to the supervising 
Inspector-General the old license when surren- 
dered, with the report of the circumstances of the 
case. New licenses may also be issued in the case 
of license lost by wreck, fire, or any other cause, 
upon a satisfactory showing of such loss to the in- 
spectors, duly sworn to. 

And inspectors will, before granting an original 
license to any person to act as an officer of steam 
vessels, require the applicant to make his written 
application upon the blank form authorized by the 
Board of Supervising Inspectors, which application 
shall be filed in the records of the inspector's office. 
Inspectors shall also, when practicable, require 
applicants for pilot's license to have written in- 
dorsement of the master and engineer of one vessel 
upon which he has served, and of the licensed 
pilot as to his qualifications. In the case of 
applicants for original engineer's license, they 
shall also, when practicable, have the indorsement 
of the master and engineer of a vessel on which 
they have served, together with one other licensed 
engineer. 

No original master's, mate's, pilot's, or engin- 
eer's license shall be issued hereafter or grade in- 
creased except upon written examination, which 



134 QUESTIONS AND ANSWERS FOR 

written examination shall be placed on file as 
records of office of the inspectors issuing said 
license. 

Any applicant for examination for license who 
has been refused for want of knowledge or other 
qualifications, may come before any local board 
for re-examination after one year has expired, on 
presentation of a letter from the board that had 
refused him. 

Any person who has served as master, com- 
mander, pilot, or engineer of any steam vessel of 
the United States, in any service in which a license 
as master, commander, pilot, or engineer was not 
required at the time of such service, shall be 
entitled to license as master, commander, pilot, or 
engineer, if the inspectors, upon written examina- 
tion as required for applicants for original license, 
may find him qualified ; Provided, That the ex- 
perience of any such applicant within three years of 
making application has been such as to qualify him 
to serve in the capacity for which he makes applica- 
tion to be licensed; but no such license shall be 
granted except under such restrictions. as may be 
prescribed by the supervising inspector of the dis- 
trict in which the applicant files his application. 
(Officers of the naval militia who are) applicants ' 
for license as master or pilot of steam vessels of the 
naval militia, after passing an examination for 
color blindness, may be examined by the inspec- 
tors as to their knowledge of the pilot rules and 
handling of vessels, and if the applicant be found 
qualified in the judgment of the inspectors, he 
may be granted a special license as master or pilot 



STEAM ENGINEERS AND ELECTRICIANS. 135 

on such vessels on the waters of the district in 
which such license is granted, and for no other 
purpose. 

All licenses issued to officers of the naval 
militia provided for in the preceding paragraph of 
this section, or in section 3 of this rule, shall be 
surrendered upon the party holding it becoming 
disconnected from the naval militia by resigna- 
tion or dismissal from such service ; and no license 
shall be issued as above except upon the official 
recommendation of the chief officer in command 
of the naval station of the State in which the 
applicant is serving. 

2. The classification of engineers shall be as 
follows : 

CHIEF. 

Chief engineer of ocean steamers. 

Chief engineer of condensing lake, bay, and 
sound steamers. 

Chief engineer of non-condensing lake, bay, 
and sound steamers. 

Chief engineer of condensing river steamers. 

Chief engineer of non-condensing river steamers. 

Any person holding chief engineer's license 
shall be permitted to act as first assistant on any 
steamers of double the tonnage of same class 
named in said chief s license. 

Engineers of all classifications may be allow r ed 
to pursue their profession upon all waters of the 
United States, in the class for which they are 
licensed, if found upon examination qualified 
therefor. 



136 QUESTIONS AND ANSWERS FOR 

FIRST ASSISTANT. 

First assistant engineer of ocean steamers. 

First assistant engineer of condensing lake, 
bay, and sound steamers. 

First assistant engineer of non-condensing lake, 
bay, and sound steamers. 

First assistant engineer of condensing river 
steamers. 

First assistant engineer of non-condensing river 
steamers. 

Engineers of lake, bay, and sound steamers 
who have actually performed the duties of engi- 
neers for a period of three years shall be entitled 
to examination for engineer of ocean steamers, 
applicant to be examined in the use of salt-water 
method employed in regulating the density of the 
water in boilers, the application of the hydrom- 
eter in determining the density of sea water, 
and the principle of constructing the instrument, 
and shall be granted such grade as the insjjectors 
may find him comjDetent to fill. 

Any assistant ' engineer of ocean steamers of 
1500 gross tons burden and over, having had 
actual service in that position for one year, may, 
if the local inspectors in their judgment deem it 
advisable, have his license indorsed to act as 
chief engineer on lake, bay, sound, or river steam- 
ers of 750 gross tons or under. 

SECOND ASSISTANT. 
Second assistant engineer of ocean steamers. 
Second assistant engineer of condensing lake, 
bay, and sound steamers. 



STEAM ENGINEERS AND ELECTRICIANS. 137 

Second assistant engineer of non-condensing 
lake, bay, and sound steamers. 

Second assistant engineer of condensing river 
steamers. 

THIRD ASSISTANT. 

Third assistant engineer of ocean steamers. 
Third assistant engineer of condensing lake 
and sound steamers. 

First, second, and third assistant engineers 
may act as such on any steamer of the grade of 
which they hold license or as such assistant 
engineer on any steamer of a lower grade than 
those to which they hold a license. 

Inspectors must designate upon the certificate of 
any chief or assistant engineer the tonnage of the 
vessel on which he may act ; 

Provided, however, That any engineer whose li- 
cense is designated by tonnage may act in similar 
capacity on any steamer of larger tonnage, pro- 
vided the engine in said steamer is not larger 
than the one to which his tonnage license re- 
stricted him. That Form 2 130 J, special license 
to engineers, be issued only to engineers in 
charge of vessels of 10 tons and under, and that 
all other licenses to engineers be issued on Forms 
2129 and 2130, according to grades specified in 
this section. 

3. Assistant engineers may act as chief en- 
gineers on high-pressure steamers of 100 tons 
burden and under of the class and tonnage or 
particular steamer for which the inspectors, after 
a thorough examination, may find them qualified. 



138 QUESTIONS AND ANSWERS FOR 

In all cases where an assistant engineer is per- 
mitted to act as first (chief) engineer, the inspec- 
tors shall state on the face of his certificate of 
license the class and tonnage of steamers or the 
particular steamer on which he may so act. 

Any (officer of the naval militia who is an) 
applicant for license as chief engineer or assistant 
engineer of steam vessels of the naval militia 
may be examined by inspectors and granted a 
special license as such, and for no other purpose, 
if, in the judgment of the inspectors, he is quali- 
fied. (See last paragraph of Section 1 of this rule. ) 

4. It shall be the duty of an engineer, when he 
assumes charge of the boilers and machinery of a 
steamer to forthwith thoroughly examine the 
same, and if he finds any part thereof in bad con- 
dition, caused by neglect or inattention on the 
part of his predecessor, he shall immediately re- 
port the facts to the local inspectors of the dis- 
trict, who shall thereupon investigate the matter ; 
and if the former engineer has been culpably 
derelict of duty, they shall suspend or revoke his 
license. 

5. No person shall receive an original license as 
engineer or assistant engineer, except for special 
license on small pleasure steamers of 10 tons 
and under, and ferryboats, saw-mill boats, pile- 
drivers, and other nondescript similar small ves- 
sels, navigated outside of ports of entry and de- 
livery, who has not served at least three years in 
the engineer's department of a steam vessel, a 
portion of which experience must have been ob- 
tained within three years preceding the applica- 
tion ; 



STEAM ENGINEERS AND ELECTRICIANS. 139 

Provided, That any person who has served a 
regular apprenticeship to the machinist trade in a 
marine-engine works for a period of not less than 
three years, and any person who has served for a 
period of not less than three years as a locomo- 
tive engineer, stationary engineer, or as an 
apprentice to the machinist trade in a locomotive 
or stationary- engine works, and any person who 
has graduated as a mechanical engineer from a 
duly recognized school of technology, may be li- 
censed to serve as an engineer on steam vessels, 
after having had not less than one year's experi- 
ence in the engine department of steam vessels, 
which experience must have been obtained either 
within one year before or one year subsequent to 
the acquisition of the skilled knowledge above 
mentioned (which fact must be verified by the 
certificate in writing of the licensed engineer or 
master under whom the applicant has served, 
said certificate to be filed with the application of 
the candidate) ; and no person shall receive li- 
cense as above, except for special license, who is 
not able to determine the weight necessary to be 
placed on the lever of a safety valve (the diam- 
eter of valve, length of lever, distance from 
center of valve to fulcrum, weight of lever, and 
weight of valve and stem being known) to with- 
stand any given pressure of steam in a boiler, or 
who is not able to figure and determine the strain 
brought on the braces of a boiler with a given 
pressure of steam, the position and distance apart 
of braces being known, such knowledge to be 
determined by an examination in writing and the 



140 QUESTIONS AND ANSWERS FOR 

report of examination filed with the application 
in the office of the local inspectors ; and no 
engineer or assistant engineer now holding a li- 
cense shall have the grade of the same raised 
without possessing the above qualifications. And 
no original license shall be granted any engineer 
or assistant engineer who cannot read and write 
and does not understand the plain rules of arith- 
metic. 

EXTRACTS FROM THE FRYE BILL. 

Section 128. That no steam vessel can obtain 
a clearance or legally proceed to sea from any port 
in the United States or navigate any waters of 
the United States which are common highways 
of commerce or open to competitive navigation, 
excepting public vessels of the United States and 
vessels of other countries, unless the engineers 
thereof have obtained and possess valid certifi- 
cates of competency or certificates of service ap- 
propriate to their several stations. 

Sec 129. That the minimum complement of 
engineers for vessels licensed for carrying pas- 
sengers shall be as follows : — Seagoing steamers : 
Twin-screw steamers with machinery of over ten 
thousand indicated horse-power, one chief engineer 
of the highest grade and nine assistant engineers, 
of whom at least three shall hold certificates as 
first assistants and three as second assistants. 

Sec. 130. Twin-screw steamers with machinery 
from five thousand to ten thousand indicated 
horse-power, one chief engineer of the grade from 
five thousand to ten thousand indicated horse- 
power and nine assistants, of whom at least three 



STEAM ENGINEERS AXD ELECTRICIANS. 141 

shall hold certificates as first assistants and three 
as second assistants. 

Sec 131. Single-screw steamers with machinery 
of over ten thousand indicated horse-power, one 
chief engineer of the highest grade and six assist- 
ants, of whom at least three shall hold certificates 
as first assistants and two as second assistants. 

Sec 132. Single-screw steamers with machinery 
of from five thousand to ten thousand indicated 
horse- power, one chief engineer of the grade from 
five thousand to ten thousand indicated horse- 
power and five assistants, of whom at least three 
shall hold certificates as first assistant and one as 
second assistant. 

Sec 133. Single-screw steamers with machinery 
of from two thousand to five thousand indicated 
horse-power, one chief engineer of the grade and 
five assistants, if there are many auxiliaries inde- 
pendent of the main engines; if there are very few 
auxiliaries, three assistants. In the first case, at 
least three of the assistants shall hold certificates 
as first assistant and one as second assistant ; in 
the second case, two shall be first assistants and 
one second assistant. 

Sec 134. Single screw steamers with machinery 
of less than two thousand indicated horse-power, 
one chief engineer of the grade, except as provided 
for the cases where first and second assistants may 
be in charge, and two assistants, of whom one 
shall be a first assistant. 

Sec 135. Paddle-wheel steamers, one chief en- 
gineer of grade according to horse-power and two 
to five assistants, depending on number of aux- 



142 QUESTIONS AND ANSWERS FOR 

iliaries. If there are five assistants three shall 
hold certificates as first assistant and one as second 
assistant; if there are less than five assistants, at 
least one shall hold a certificate as first and one as 
second assistant. 

Sec. 136. Steamers navigating lakes, bays, 
sounds, and rivers: There shall in every case be 
a chief engineer of the grade corresponding to the 
horse-power, except, as elsewhere provided, when 
first and second assistants are allowed in charge, 
and a number of assistants depending on the size 
and complexity of the machinery and the duration 
of the trip between terminals; but in no case shall 
any steamer on routes of longer than fourteen 
hours' duration be allowed to run with less than 
two engineers, including the chief engineer, and 
when there is only one assistant he shall hold a 
certificate at least as high as second assistant, pro- 
vided that in the case of small pleasure steamers 
of ten tons and under a third assistant engineer 
may have charge of the machinery. 

Sec. 137. That on every steamer engineers hold- 
ing a certificate of higher grade than that required 
may perform the duties of the lower grade. 

Sec 138. That before a steamer is licensed for 
carrying passengers the supervising inspector of 
the district must be notified of the service she is 
intended to perform, and he shall make personal 
inspection of the machinery and decide upon the 
minimum complement of engineers in those cases 
where it is not specifically provided for. In his 
decision he will be governed by the arrangement 
and complexity of the machinery, the subdivision 



STEAM ENGINEERS AND ELECTRICIANS. 143 

of water-tight bulkheads, and all other matters 
which increase the difficulty of properly caring for 
the machinery. 

Sec. 139. That in all cases, including those 
specifically provided for, he is authorized to in- 
crease the complement if, in his judgment, the 
complexity and arrangement of the machinery, the 
number of auxiliaries, and the arrangement of 
bulkheads make it necessary to the adequate care 
and supervision of the machinery while in op- 
eration. Should the owner of the steamer deem 
the number assigned too great he may appeal to 
the Supervising Inspector-General, transmitting 
plans of the vessel and machinery in sufficient 
detail to enable an intelligent decision to be ren- 
dered. 

Sec. 140. That, in the case of steamers used 
entirely as freight-carriers and not carrying pas- 
sengers, the number of engineers shall be decided 
by the supervising inspector after a personal in- 
spection and knowledge of the intended service. 

Sec 141. That in all cases there shall be a 
chief engineer of the appropriate grade, except as 
elsewhere provided, when first and second assist- 
ants are allowed in charge. 

Sec 142. That, if the vessel is a seagoing one 
and the duration of the voyage is more than forty- 
eight hours, there shall always be at least three 
engineers, including the chief, and one of the as- 
sistants must hold a certificate as first assistant. 
If the voyage lasts less than forty-eight hours 
there may be two engineers only. 

Sec 143. That if the vessel does not go to sea, 



144 QUESTIONS AND ANSWERS FOR 

but navigates only bays, sounds, lakes, and rivers, 
there must be two engineers if the average num- 
ber of hours under way per day exceeds ten or if 
the number of hours for any single regular run 
exceeds twelve. Where the duration of the trip is 
less than herein specified one engineer only will 
be required. 

Sec. 144. That in the case of pile-drivers, saw- 
mill boats, and other small craft, not carrying 
passengers, a third assistant engineer may have 
charge of the machinery if it does not exceed one 
hundred indicated horse-power. That a special 
certificate may be granted authorizing the holder 
to act as engineer on steamers of ten tons and un- 
der, not carrying passengers or freight for pay, if 
the local inspectors are satisfied that the candidate 
is competent. 

Sec 145. That the classification of engineers 
in the merchant service of the United States shall 
be as follows : Chief engineer of machinery ex- 
ceeding ten thousand indicated horse-power, chief 
engineer of machinery between five thousand and 
ten thousand indicated horse-power, chief engineer 
of machinery between two thousand and five 
thousand indicated horse-power, chief engineer of 
machinery of two thousand indicated horse-power 
and less, first assistant engineer, second assistant 
engineer, third assistant engineer. 

Sec 146. That first assistant engineers may act 
as chief engineers of engines of less than three hun- 
dred indicated horse-power and second assistant 
engineers may have charge of engines of less than 
one hundred indicated horse-power, provided the 



STEAM ENGINEERS AND ELECTRICIANS. 145 

vessel in which such engines are placed is used in 
river or harbor service only or does not go to sea 
beyond twenty miles. 

Sec 147. That a chief engineer for engines of 
ten thousand indicated horse-power and upward 
must be at least thirty years old and must have 
served at least five years at sea as a chief engineer 
or first assistant with engines of over two thousand 
indicated horse-power. He must be able to super- 
intend the construction of machinery for two 
thousand indicated horse-power and upward, and 
to devise and direct the repair of any accident to 
the machinery likely to occur. He must be able 
to secure a general average of ninety per centum 
on the examination for chief engineer hereinafter 
provided for and an average of seventy-five per 
centum on such additional questions as may be 
given by the examining board for this grade and 
the next lower. 

Sec 148. That the requirements for a chief en- 
gineer for machinery of from five thousand to ten 
thousand indicated horse-power shall be the same 
as for a chief engineer for machinery of over ten 
thousand indicated horse-power, except that he 
shall only be required to secure an average of 
eighty per centum on the general examination for 
chief engineer and seventy per centum on the spe- 
cial questions for this grade and the next higher. 

Sec 149. That a chief engineer for machinery 
of from two thousand to five thousand indicated 
horse-power must be at least thirty years of age 
and have served at least five years as chief engineer 
of a seagoing steamer or as first assistant with 



146 QUESTIONS AND ANSWERS FOR 

engines from two thousand to five thousand indi- 
cated horse-power. He must be able himself to do 
or direct the adjustment of any part of the engines 
and to run the lines for them and erect them in 
the vessel. He must be conversant with work on 
boilers and piping and able to direct the repair of 
any accident to them as well as the accidents likely 
to occur to the engines. He must secure seventy - 
five per centum on the general examination for 
chief engineer. 

Sec. 150. That a chief engineer for machinery 
of two thousand indicated horse-power or less 
must be at least thirty years of age and must have 
served at least five years as a first assistant or 
three years as a first assistant with engines of two 
thousand indicated horse-power and over in a sea- 
going ship. He must be able to make himself 
or to direct the making of any ordinary repairs 
to any part of the machinery. He must secure 
sixty-five per centum on the general examination 
for chief engineer. 

Sec. 151. That a first assistant engineer must 
be at least twenty-five years of age and must have 
served at least two years as a second assistant. 
He must understand the working of every part of 
the machinery and be able himself to make the 
adjustment directed by the chief engineer. He 
must understand the use of all the mechanics' 
tools employed in work about marine machinery 
and be himself skilled at some trade connected 
with the making or fitting of such machinery. He 
must secure at least sixty-five per centum on the 
examination for his grade. 



STEAM ENGINEERS AND ELECTRICIANS. 147 

Sec. 152. That a second assistant engineer must 
be at least twenty-three years of age and must 
have served at least one year as a third assistant. 
He must understand the working of marine ma- 
chinery and be able to start, stop, and care for it 
while in motion. He must understand the usual 
remedies for such things as heated journals, low 
water, and foaming, and be able to fit and adjust 
bearings, pack stuffing boxes, and do other ordi- 
nary work about marine machinery. He must be 
proficient in some trade connected, with the build- 
ing of marine machinery. He must secure at 
least sixty-five per centum on the examination for 
his grade. 

Sec. 153. That a third assistant engineer must 
be at least twenty-one years of age. He must 
either be a machinist by trade and have had at 
least one year's experience with engines and 
boilers on a vessel or on shore, or be a journeyman 
mechanic in a trade connected with the building 
of marine machinery, and have had one year's 
experience in the engine department of a steam 
vessel or two years' experience with engine and 
boiler on shore, or have had at least three years' 
experience in the engine department of a steam 
vessel. He must secure at least sixty-five per 
centum at the examination for his grade. 

Sec 154. That the examinations for the two 
higher grades of chief engineer shall be held by a 
board consisting of the supervising inspector of 
the district and two local inspectors of boilers, 
and shall take place not oftener than twice a year, 
and only then if there are applicants. The exam- 



148 QUESTIONS AND ANSWERS FOR 

ination for the other two grades of chief engineer 
shall be held by a board of three local inspectors 
of boilers. These shall be held at least twice a 
year, and once a quarter if there are more than 
five applicants. 

Sec. 155. The examination for first, second, and 
third assistant engineers shall be conducted by the 
local inspector of boilers at least once each quarter 
if there are applicants. 

Sec. 156. That when an applicant for any of 
the grades of engineers hereinbefore enumerated 
has not had the service in the merchant marine of 
the United States contemplated, but has had 
equivalent service with marine machinery else- 
where, of which he can produce satisfactory evi- 
dence, he shall be admitted to examination, and, 
if found to be possessed of the requisite degree of 
proficiency, shall be certificated the same as if his 
previous service had been in the merchant marine 
of the United States. 

Sec 157. That applicants for every grade of 
engineer must satisfy the examining board that 
they are of sober and correct habits ; and, if 
called upon by the examining board to do so, 
must furnish the names of the vessels on which 
they have previously served, together with the 
names of the masters and chief engineers, to whom 
the board may address interrogatories if they deem 
it necessary to establish the character of the appli- 
cant. If the service has been on shore the testi- 
monials must be signed by an employer. 

Sec. 158. That nothing contained in the fore- 
going rules is to be construed to deprive any engi- 



STEAM ENGINEERS AND ELECTRICIANS. 149 

neer of the certificate which he now holds or of 
the privilege of renewal in accordance with the 
rules heretofore existing, except as hereinafter 
provided. 

Sec 159. That, if an engineer with a certificate 
desires to qualify for duty with machinery of 
greater horse-power than that of the class with 
which he is serving, he must make application 
and pass the examination provided for above for 
such higher class of machinery, and this is to 
apply to the various grades of assistants as well as 
to those of chief ; that is, an engineer may con- 
tinue to hold his certificate for the same kind and 
power of machinery, but if he desires to serve 
with larger or different machinery he must pass 
the examination for the grade he desires to hold, 
as herein provided. 

Sec 160. That solutions of problems and an- 
swers to questions shall be given in ink, and no 
candidate will be permitted to leave the examiner's 
room until a paper is finished and handed in, and 
all the examination papers shall be referred to the 
Supervising Inspector-General of Vessels, with the 
examiner's recommendations indorsed thereon 
and placed on file. Any examiner, officer, or em- 
ployee of the inspection service assisting a can- 
didate in any manner in the solution of his ques- 
tions will be dismissed from the service. 

Sec 161. That, in case it shall be proved by 
oath or affirmation that the certificate of compe- 
tency or the certificate of service of a master, 
mate, or engineer has been lost, destroyed, or 
unintentionally mislaid, the same shall be reissued 



150 QUESTIONS AND ANSWERS FOR 

from the records in the office of the Supervising 
Inspector-General of Vessels, through the inspec- 
tor to whom the application for renewal is made. 

Sec. 162. That all certificates of competency 
and of service shall be made in duplicate, one 
copy of which, under the seal of the Treasury 
Department and hand of the Supervising Inspec- 
tor-General of Vessels, shall be issued to the per- 
son entitled to the same by the inspector before 
whom the candidate appeared for examination, by 
which inspector the certificate shall be sealed and 
countersigned. 

Sec. 163. That the qualifications required for 
the several grades below mentioned shall be as 
follows : — Third assistant engineer : First. He 
must know the names of the different parts of a 
steam engine and boiler and of the fittings and 
mountings, including condenser and pumps. 

Second. He must be able to lay and start fires 
and raise steam and understand the precautions to 
be taken to prevent injury to the boiler ; must 
know how to " tend water," fire, and clean fires ; 
also what to do in case of low water. 

Third. He must be able to start, stop, and re- 
verse the engine, and know what precautions to 
observe in starting to prevent injury to engines 
and boilers. 

Fourth. He must know what to do to engines 
and boilers in case of foaming, and the course to 
be pursued in the case of hot bearings. 

Fifth. He must be able to read the steam and 
vacuum gauges and other instruments about the 
machinery intelligently. 



STEAM ENGINEERS AND ELECTRICIANS. 151 

Sixth. He must know the first four rules of 
arithmetic and be able to write a legible hand. 

Sec. 164. Second assistant engineer : First. He 
must be able to give a description of the boilers 
and engines in common use on board ship and of 
the fittings and connections used with them, in- 
cluding the way in which boilers are braced, 
and the use and management of the different 
valves, cocks, levers, and so forth. 

Second. He must be able to tell how ordinary- 
repairs to boilers are made, such as hard and soft 
patching., riveting, expanding tubes, calking 
seams, plugging leaky tubes, and so forth. 

Third. He must understand the use of the 
thermometer, barometer, salinometer, steam and 
vacuum gauges, gauge cocks, and glass water 
gauges, and in general all other fittings about the 
machinery. 

Fourth, He must be able to tell what foaming 
and priming are, how discovered, and their effects 
on boilers and engines, and what is done to stop 
them. 

Fifth. He must be able to tell the course to be 
pursued in raising steam and getting engines and 
boilers ready for work, and the process followed 
when the machinery is no longer needed on reach- 
ing port, including both the cases when the fires 
are to be banked and when the boilers will not be 
needed for several days. 

Sixth. He must be able to tell how to ascertain 
whether the journals are working properly and 
what to do to prevent heating, and to remedy it if 
it does occur. 



152 QUESTIONS AND ANSWERS FOR 

Seventh. He must be able to tell how firing 
should be conducted and how a fire should be 
cleaned. 

Eighth. He must be able to tell what to do in 
case of low water. 

Ninth. He must be able to tell how to lay up 
packing and how to pack stuffing boxes, pump 
pistons, and so forth. 

Tenth. He must know enough arithmetic to be 
able to work any problem under the fundamental 
rules and common fractions. He must be able to 
write a legible hand and write an ordinary letter 
so as to show a fair knowledge of spelling and 
grammar. 

Sec. 165. First assistant engineer : First. Fa- 
miliarity with all the ordinary types of engines 
and boilers ; explanation of the different parts, 
their object, and method of working. 

Second. Duties in raising steam and getting un- 
der way ; in maintaining a good performance 
while under way ; and when ship is anchored 
or secured. 

Third. Description of common derangements 
that may happen, such as foaming, hot journals, 
and so forth, with account of procedure to remedy 
them ; also tell what should be done to prevent 
them. 

Fourth. Repairs : Tell how patches are put on 
a boiler, tubes expanded, and so forth. 

Fifth. Adjustment of journals and valve gear ; 
setting of valves. 

Sixth. Use of steam-engine indicator and ex- 
planation of diagrams taken with it, as well as 



STEAM ENGINEERS AND ELECTRICIANS. 153 

calculation of indicated horse-power from dia- 
gram. 

Seventh. Expansion of steam ; object of ; how 
accomplished in practice. 

Eighth. Familiarity with instruments used about 
machinery, steam and vacuum gauges, thermom- 
■ eter, barometer, and so forth ; how they should 
be fitted to insure accurate readings. 

Ninth. Fittings and mountings of engines, boil- 
ers, and auxiliaries ; description of safety valves, 
safety-feed arrangements, gauge cocks, and glass 
gauges on boilers, and so forth. 

Tenth. Description of the steam pumps in com- 
mon use, and explanation of any derangements to 
which the}' are liable. 

Eleventh: Problems in connection with measure- 
ment of coal bunkers, oil tanks, position of weight 
on safety-valve lever, and so forth. 

Twelfth. Acquaintance with the rules of arith- 
metic through percentage and proportion, and of 
mensuration, to enable the solution of such prob- 
lems as in paragraph eleven. Legible handwriting 
and knowledge of spelling and grammar. 

Thirteenth. Ability to make a sketch, with fig- 
ured dimensions, from the machinery, so that in 
case of a broken part a new one could be made 
from his sketch. 

Sec 166. Chief Engineer. — First Boilers: These 
shall include all the common makes of boilers 
likely to be found in any vessel on which the ap- 
plicant would serve, and also a knowledge of how 
the various parts are put together, the advantages 
of different kinds of riveting, the methods of brae- 



154 QUESTIONS AND ANSWERS FOR 

ing, the attachments commonly used, including 
improved forms, and the use of forced draft, and 
the changes in boilers consequent thereon. 

Second. Engines: The different kinds in com- 
mon use, including those used with paddle wheels; 
description of their different parts and methods of 
fitting them together. 

Third. Valves: Different kinds in common use 
and advantages of forms now in use over older 
ones which have been abandoned. How to set 
valves. Cut-off, how effected, and how different 
points of cut-off change dimensions of valve. De- 
scriptions of modern valve gears with screw and 
paddle engines, explanation of working, and how 
variable cut-off is secured with them. Derange- 
ments common to valves and valve gears. 

Fourth. Journals: How fitted in different places, 
provision for lubrication for preventing heating, 
and for taking up wear. This is to include shaft 
and connecting rod journals and thrust bearings. 

Fifth. Condensers : Object of, explanation of 
forms in common use. Methods of packing tubes, 
preventing crawling, and for good distribution of 
the steam. 

Sixth. Pumps : Air, circulating, feed, and aux- 
iliary pumps : Description of the varieties in 
common use. Description of their connections, 
as of air and circulating pumps to the condenser. 
Vacuum, how produced ; value of and how af- • 
fected by derangement of pumps or peculiarities 
of working of engine. 

Seventh. Propelling instruments, including screw 
and paddle wheel : Description of the forms in 



STEAM ENGINEERS AND ELECTRICIANS. 155 

common use and explanation of the advantages of 
forms now in use over older ones. Description of 
methods of securing propelling instruments to 
shafts and of bearings for same. 

Eighth. Electric machinery: Practical descrip- 
tion of dynamo-electric machines as fitted on board 
ship and of the parts requiring adjustment. Acci- 
dents likely to occur to dynamos, and what to do 
to remedy them. Practical points on the wiring 
of ships, and points to be looked after to insure 
good working. Electric lamps and connection to 
mains. 

Xinth. Refrigerating and hydraulic machinery: 
Description of the forms commonly fitted on board 
ship. Description of process of working and state- 
ment of points to be looked after to insure good 
working. 

Tenth. Care of machinery: This will include 
questions in regard to precautions to be observed 
in raising steam so as to prevent injury to engines 
and boilers; precautions to be observed to prevent 
derangements while in operation ; procedure on 
reaching port and laying up for a few days; and 
procedure when engines and boilers are to be laid 
up for a long period, say of several months or more. 

Eleventh. Accidents liable to occur, even with 
care, and how to remedy them. 

Twelfth. Accidents liable to occur due to care- 
lessness or neglect, and what should be done if 
they do occur. 

Thirteenth. Accidents that have occurred in ap- 
plicant's own experience, or of which he knows, 
and what was done to remedy them. 



156 QUESTIONS AND ANSWERS FOR 

Fourteenth. List of machine and hand tools 
usually carried on board ship, and general idea of 
work that can be done on board in any case of 
necessity. 

Fifteenth. Economy in the use of stores. Tell 
how engines should be run, firing of furnaces con- 
ducted, and lubrication looked after and regulated 
so as to secure the best economy. Effect of change 
of pitch of propeller on econonw. Also of varia- 
tion in ratio of heating to grate surface. 

Sixteenth. He must be acquainted with the 
principles of expansion and the modern theory of 
heat, and be able to solve, with the assistance of 
his own books or without books, according as the 
examination papers may be set, questions in econ- 
omy and duty in connection with engines and 
boilers. 

Seventeenth. He must understand how to apply 
the indicator and to draw the proper conclusion 
from diagrams, and to construct the approximate 
diagrams for any given data. 

Eighteenth. He must be able to produce, with- 
out a copy, a fair working drawing of any of the 
machinery, with figured dimensions fit to work 
from. 

Nineteenth. Strength of materials: Calculations 
for thickness of boiler shells, size of bolts to stand 
a given strain, and so forth. 

Twentieth. Inspection of coal, oil, and so forth. 
Points to be desired and those to be avoided. 

Twenty-first. He must be able to explain the 
formation of scale and the precipitation of salt. 
and the precautionary means adopted in respect 



STEAM ENGINEERS AND ELECTRICIANS. 157 

thereto, with jet condenser and with surface con- 
denser. 

Twenty-second. He must understand the general 
principles involved in the construction of the 
vacuum and steam gauges, of the barometer, ther- 
mometer, and salinometer. 

Twenty -third. He must be familiar with the 
general results obtained from past experience in 
relation to corrosion, pitting, and galvanic action 
in boilers, and the use of zinc and of soda in 
boilers. 

Twenty-fourth. He must possess an intelligent 
knowledge of the properties of the lubricants, 
boiler cements, and india rubber in general use in 
steamers. 

Twenty-fifth. He must understand the cause of 
spontaneous combustion and the formation of ex- 
plosive gases in coal holes and the precautionary 
measures proper to prevent accidents from these 
causes. 

Sec 167. Special examination for the two high- 
est grades of chief engineer: First Theory of the 
steam engine. Explanation of the advantages of 
multiple expansion engines, steam jacketing, high 
speeds, and so forth. 

Second. Theory of boiler design and construc- 
tion. Effect of changes in ratios of heating and 
grate surface area through tubes and chimney. 
Production of draft, natural and forced. Influence 
of proportions on economy of steam production. 
Features of design requiring special care to insure 
good circulation, prevent foaming, and so forth. 

Third. Theory of boiler incrustation and corro- 



158 QUESTIONS AND ANSWERS FOR 

sion and explanation of means taken to prevent 
and remedy effects of same. 

Fourth. Theory of condensers and connected 
pumps. Elements necessary to economy and effi- 
ciency. 

Fifth. Design of machinery and boilers of a 
given power. 

Sixth. Strength of materials. Ability to calcu- 
late necessary size of any part of the machinery 
and boilers. 

Seventh. Theory of friction as presented in ma- 
rine machinery: Anti-friction metals. Lubrica- 
tion and lubricants, including inspection and tests 
of latter. 

Eighth. Valves and valve gears. Thorough 
knowledge of the various kinds, the theory of their 
action, advantages and disadvantages, and what 
considerations govern the choice of a particular 
valve gear for special use. 

Ninth. Theory of electric light installations on 
board ship, including details of dynamos, wiring, 
safety fuses, and so forth; care of dynamos; pre- 
cautions to be followed in wiring and so forth. 

Tenth. Theory of refrigerating machinery and 
precautions to be looked after in its installation. 

Eleventh. Theory of hydraulic machinery, in- 
cluding pumps, hoists, steering gear, and so forth; 
details of installation and so forth. 

Twelfth. Building machinery and erection of 
same on board ship. The applicant must be able 
to tell the whole process of building any part of 
the machinery and boilers, and give the details of 
its alignment and erection on board ship. 



STEAM ENGINEERS AND ELECTRICIANS. 159 

Thirteenth. Questions on supposititious break- 
downs will be given, and the applicant asked for 
his explanation of the best method of repair, if a 
repair is practicable, or what should be done to 
get the vessel into port if the break cannot be re- 
paired. 

Fourteenth. Questions will be given to test the 
ability of applicant to estimate the time and cost 
for repairs to be made in port, full details of the 
parts to be repaired being given. 



QUESTIONS FOR THIRD ASSISTANT ENGINEERS. 

Q. What is a damper, and where is it placed ? 

A. A damper is an apparatus for controlling the 
supply of air to boiler furnaces. They are fitted 
sometimes in the funnel and sometimes at the 
mouth of the ashpit. They are to be closed 
whenever the engines are stopped; when there is 
priming in the boiler, or in any case where it is 
desired to diminish combustion. 

Q. When there are no dampers, what is done 
instead of closing the damper, and what is the 
objection to this ? 

A. The doors of the smoke boxes and the fur- 
naces are opened. This is very objectionable, be- 
cause the sudden rush of cold air striking the 
heated surface of the boiler produces contractions 
which are liable to result in cracked tubes or plates 
and in leaks. 



160 QUESTIONS AND ANSWERS FOR 

Q. What are the necessary fittings of a marine 
boiler ? 

A. A funnel with its air casings, the up-takes, 
smoke-boxes, and doors, fire doors, bars, bridges; 
main stop-valves, safety valves, and thier drain 
pipes; feed check valves ; blow-off and scum 
cocks; water gauge glasses, water gauge cocks, and 
steam whistle. 

Q. Through what apparatus does the steam 
pass from the time it leaves the boiler until it re- 
turns again ? 

A. The boiler, steam pipes, cylinder, condenser, 
air-pump, hot well and feed pump. 

Q. How many blow-off cocks are there and why ? 

A. One on the bottom of the boiler and one on 
the ship's side. When both are open water will 
run from the sea into the boiler if steam is not up; 
if steam is up its pressure will blow the water out. 
The object of having two cocks is to provide 
against one of them being open. 

Q. Suppose that the upper cock of the water 
gauge should be closed or choked up, where would 
the water stand ? 

A. At the top of the glass. 

Q. And if the upper one were opened with the 
lower one closed ? 

A. The water would remain at the same level 
that it had. 



STEAM ENGINEERS AND ELECTRICIANS. 161 

Q. In testing the height of the water by the 
gauge cocks, which one would you open first and 
what should come out ? 

A. The bottom one. Water. 

Q. Which one would you open next ? 

A. The top one, and I should expect steam to 
come out. 

Q. Suppose that water comes out of the top one 
also, what would you do ? 

A. I would blow off until water was at the 
proper level. 

Q. Suppose that steam had come out the bot- 
tom one, what would you have done ? 

A. I would check the tires instantly, closing the 
dampers, then I would draw them. I would shut 
down the engine, and as soon as the boiler had 
cooled off would pump in water. I would examine 
both ends of the boiler to see if the tubes are leak- 
ing, and if they are, I would attempt to stop them 
by expanding the ends; if this did not remedy the 
leaking of all, I would plug up the worst ones. 

Q. How would you change the water in the 
boiler when the steam is up ? 

A. By increasing the feed and opening the scum 
cock. 

Q. Suppose that the scum cock is stuck fast, 
what would you do ? 

A. I would open the blow-off cocks. 



162 QUESTIONS AND ANSWERS FOR 

Q. Suppose that upon attempting to relieve the 
pressure on the boilers through the safety valve 
you found that it was stuck, what would you do ? 

A. I would check the fires and draw them, and 
as soon as the boiler was sufficiently cool would 
repair the valve. 

Q. What might be the effect of letting the water 
in the boiler get too low ? 

A. The top of the combustion chamber and the 
tubes might be burned, or it might even cause an 
explosion. 

Q. What might be the effect of too high water 
in the boiler? 

A. Priming, and possibly the breaking of the 
cylinder head. 

Q. Explain how you would proceed in starting 
a new fire in the boilers. 

A. I would first see that the valves in the water 
gauge were open and would try the gauge cocks. 
Having found that the water level was all right I 
would cover the grate bars with a thin layer of 
coal; then, if I had fire in another boiler, I would 
take two or three shovelfuls from this other 
boiler and put it on the grate and throw on either 
soft coal and wood or shavings and then gradually 
add fresh coal. I would open the upper gauge 
cock in the boiler so as to let the air that is con- 
tained in the water escape. 



STEAM EXGIXEEKS AND ELECTRICIANS. 163 

Q. How would you clean your fires ? 

A. I would let the fire burn down on one side 
from front to back, meanwhile keeping the other 
side in good condition; then I would pull out the 
ashes and clinkers from the side that had burned 
down, cleaning all the walls at the same time, and 
Would pull over the good part of the fire from the 
other side and put on fuel as fast as it was needed; 
then, after allowing the clinkers and ashes to cool, 
I would pull them out, and proceed in the same 
way as on the first side. 

Q. What regulates the depth of fuel to be 
carried on the grates ? 

A. The draft. 

Q. What is priming, and what causes it ? 

A. Priming is tlie carrying over of water from 
the boiler into the engine in the form of a spray. I* 
may be caused by poor design of the boiler giving 
too small a steam space ; or, in a well-designed 
boiler, it may be caused by canying the water at 
too high a level and by irregular firing. 

Q. How can you tell whether there is priming 
or not ? 

A. Priming often causes a clicking sound in the 
cylinder of the engine. By opening a valve and 
allowing steam to escape into the air the appear- 
ance of the jet will tell whether the steam is dry 
or not. If it has a milky or cloudy appear- 



164 QUESTIONS AND ANSWERS FOR 

ance close to the orifice there is evidently prim- 
ing. 

Q. What would you do in case you found there 
was priming ? 

A. I would open the cylinder drip cocks and 
close the damper of the boiler and lower the water 
level. 

Q. What sometimes causes the appearance of 
flame at the top of a funnel, and is this desirable 
or not ? 

A. Whenever flames come out of the top of a 
funnel this shows that the gases have not been 
united within the combustion chamber as they 
should have been. The cause of this would be a 
too small supply of air in the combustion chamber. 
Combustion taking place outside of a boiler is 
extremely undesirable, as it means a waste of fuel. 

Q. How can you prevent salting of the boiler? 

A. By scumming and blowing off a part of the 
water in the boiler. 

Q. How can you tell the density of the water in 
the boiler ? 

A. By the reading of the salinometer. 

Q. What density is proper ? 

A. A density such that the salinometer reads 
about -^-. 

Q. How is the salinometer made, and how do 
you use it ? 



STEAM ENGINEERS AND ELECTRICIANS. 165 

A. The salinometer consists of a glass bulb car- 
rying a weight on its bottom and a graduated 
stem attached to its top, the graduations being 
in 32ds or 33ds. To use it, all that is necessary 
is to put it in a vessel of the fluid whose density 
it is desired to know, and it will sink to the amount 
corresponding to the density. The reading of 
the stem, which is just even with the surface of 
the liquid, will tell what the density is. 

Q. What are scum cocks ? 

A. They are cocks placed on a boiler for the 
purpose of getting rid of any dirt which may be 
floating on the surface of the water in the boiler; 
the}' are placed, therefore, a little below the usual 
water line. They are connected by a pipe which 
leads to another coo 1 ! on the vessel's side. 

Q. When you receive an order to stop the 
engines, what would you shut and what would you 
open? 

A. I would shut the throttle valve and the sea 
injection valve and would also close the dampers. 
I would open the safety valve. 

Q. What would you do before starting an 
engine ? 

A, I would warm it up by opening the drain 
cocks and blowing steam through it and the con- 
denser. I would also examine the various valves, 
including the injection and discharge valves, to see 



166 QUESTIONS AND ANSWERS FOR 

that they are open or free to open, as the case 
may be. 

Q. Explain in detail what valves and cocks 
should be opened before starting the engine. 

A. The main stop valve, the check valve, the 
drain cocks on cylinders and jackets, the blow- 
through cocks, the sea inlet for circulating water. 

Q. What would you do in case the engine were 
racing ? 

A. I would attach the governor, if there were 
one, and I would stand at the throttle valve ready to 
close it as the steam rises. I should also run with 
a lowered boiler pressure and would ease up on 
the injector. 

Q, Why is soda sometimes put into a boiler, and 
what kind of soda is used ? 

A. Common washing soda is put in boilers in 
order to neutralize any acid that may be in the 
feed-water which might cause pitting. 

Q. How can you prevent the formation of black 
smoke ? 

A. Black smoke is due to imperfect combustion 
and can generally be prevented, partially, by ad- 
mitting air into the combustion chamber so as to 
unite with the combustion gases. There is usually 
in marine boilers a small door underneath the rear 
bridge which can be opened so as to admit the 
necessary amount of air. 



STEAM ENGINEERS AND ELECTRICIANS. 167 

Q. Suppose that one of a set of boilers does not 
get the proper amount of feed, although the check 
valve is sufficiently open; what might cause this 
trouble ? 

A. There are several possible causes, such as 
leaky joints or pipes or feed pump glands or a leaky 
feed relief valve. It may be that the steam pres- 
sure in this boiler is higher than in the others, or 
the suction may be partially closed up between 
the suction cock and hot well. The feed suction 
discharge valves may not be tight. 

Q. About how many tons of coal should you 
expect to burn per day in six furnaces, each hav- 
ing a width of 3 feet and about the usual length ? 

A. The usual length being about 6 feet, the 
total grate area would be 6 X 3 X 6, or 108 square 
feet. Each square foot will burn about 15 pounds 
per hour; therefore, the total number of pounds 
burned per hour would be 1620. and per day of 24 
hours would be 38,880. Since there are 2240 
pounds in a ton, the number of tons would be 17 J, 
nearly. 

Q. How many cubic feet are occupied by a ton 
of coal ? 

A. About 35. 

Q. How would you calculate the amount of 
stress on a boiler stay ? 

A. Multiply the area (in square inches) of the 



168 QUESTIONS AND ANSWERS FOR 

space supported by the stay by the pressure car- 
ried on the boiler, and divide the product by the 
area of the stay. 

Q. How would you calculate the proper weight 
for a lever safety valve so that it will blow off at 
a given pressure ? 

A . See ' ' Roper' s Catechism, ' ' page 50. 
Q. Su]3pose you have been using 8 gallons of 
oil a day, costing 85 cents per gallon, and you now 
by more careful attention to the lubricators cut 
down the consumption to 6 gallons per day, but 
you use a little better oil, costing 95 cents per gal- 
lon, what will be the difference in expense for one 
month ? 

A. The original cost per day was 85 times 8 
cents, or $6.80. 
The cost with the new oil is 95 times 6 

cents, or $5.70. 
The gain per day is $6.80 less $5.70, or 

$1.10. 
The gain in one month is $1.10 times 30, or 
$33.00: (Ans.) 
Q. A vessel has, in order to complete her voyage, 
a distance of 2100 miles to go ; it actually takes 
150 hours to make the run, what is the average 
speed per hour ? 

A. 2100 -f- 150 = 13J miles per hour. (Ans.) 
Q. From 7 a.m., on the 20th of June, to the 3d 



STEAM ENGINEERS AND ELECTRICIANS. 169 

of August, 10 p.m., the coal consumption was 3168 
tons; the distance passed over in this time was 
14,784 knots; what is the average consumption of 
coal and average speed ? 

A. The time is 44 days 15 hours, or 1056 hours. 
The coal consumption per hour is 3168 -f- 

1056, or 3 tons. 
The coal consumption per day is 24 X 3, 

or 72 tons. 
The speed is 14,784 -v- 1056, or 14 knots per 

hour. (Ans.) 

Q. If the counter stands to-day at noon at 
95,321 and to-morrow at noon it stands at 98,237, 
what will be the average number of revolutions 
per minute ? 



98237 
95321 


60)243(4^ (Ans.) 
240 


12)2916(243 
24 


3 


51 

48 




36 
36 





Q. Suppose at 10 a. m. the counter stands at 
54,606, and the engine is making 60 revolutions 
per minute, at what time will the counter stand 
100,026? 



170 



QUESTIONS AND ANSWERS FOR 



A. 100026 
54606 


60)757(12 hrs. 37 minutes. 
60 


60)45420(757 
420 


157 
120 


ft 


342 

300 


37 




420 
420 


10.37 p.m. 


(Ans.) 



Q. Suppose that an engineer receiving « 
week strikes for an increase of S3 per week; 
idle for ten weeks, but at the end of that tir 
ceives employment at the higher rate, how loi 
it take him to make up the wages he lost whiL 
A. His lost wages are 15 X 10, or $150. 
It will take him 150-7-3 weeks, or 50 
to make up for the lost time. (An 
Q. Suppose that the rate of burning per 
foot of grate surface per hour is 20 pouin 
suppose that a ton of the coal used occ 
space of 40 cubic feet; how many cubic 
coal would be burned in ten hours on a 
feet by 3 feet? . 

A. 6 X 3 X 20 X 10, or 3600 = nuif 
pounds of coal burned. 
2240 pounds occupy 40 cubic feet, or 56 

pounds occupy 1 cubic foot. 
3600 pounds occupy 3600 -r- 56, or 64$fc or 
64-f- cubic feet. ( Ans. ) 



d a 

e is 
; re- 
will 

die? 

eeks 

) 

mare 
f and 
ries a 
iet of 
rate 6 

of 



STEAM ENGINEERS AND ELECTRICIANS. 171 

Q. You have 6 furnaces, each 6 feet long by 3 
feet wide, the rate of burning is the same as the 
pn jecling question, and every pound of coal e vap- 
or o+y 3S 9 pounds of water; how many tons of coal 
wi be used in ten hours, and how many tons of 
wa r will be evaporated ? 

. The area of grates is 6 X 6 X 3, or 108 
square feet. 
The number of pounds burned per hour is 

103 X 20, or 2160. 
The number of pounds of water evaporated 

is 2160 X 9, or 19,440. 
The number of tons of coal burned in 10 
hours is 2160 X 10 -f- 2240, or 9^, or 
91-i- tons. 
?he number of tons of water evaporated is 9 
times this amount, or 86-^f , or 86-j-^- tons. 
(Ans.) 
Q. . vessel starts on a voyage of 1200 miles 
with ) tons of coal ; after having steamed 500 
miles is found that 30 tons of coal have been 
consumed. If the remainder of the voyage is 
ma.' the same rate of steaming, how much coal 
will be left at the end of the voyage ? 

A. 30 -I- 5 = 6, the number of tons used per 
hundred miles. Therefore, 1200 miles will require 
12 X 6, or 72 tons. Hence, there will be 8 tons 
left at the end of the voyage. 



3145 5905 

2516 4480 



172 QUESTIONS AND ANSWERS FOR 

Q. In 24 hours steaming the tally of baskets of 
coal for each watch was 100, 105, 110, 107, 104, 
103. If each basket weighed 45 pounds, what 
would be the consumption per day in tons ? 

A. 100 629 2240)28305(12 tons 1425 lbs. 

105 45 2240 (Ans.) 

110 
107 
104 
103 28305 1425 

629 

Q. An engineer who receives $15 per week lays 
aside ^ of his pay; how many weeks will it take 
him to save up $250 ? 

A. 15 -=- 6 = 2J dollars, the amount saved per 
week ; 250 -=- 2-J- = 100, the number of weeks 
necessary. 

QUESTIONS FOR SECOND ASSISTANT ENGINEERS. 

[In addition to the following, the candidate should be 
prepared to answer the questions for third assistant engi- 
neers.] 

Q. Trace the passage of steam from the boiler, 
naming all the parts and valves which it passes 
from the time it leaves the boiler until it comes 
back as feed-water. 

A. Steam passes from the dome or dry pipe 
through the stop valve into the main steam pipe ; 



STEAM ENGINEERS AND ELECTRICIANS. 173 

from the main steam pipe it passes through another 
stop valve, through a separator, through the throt- 
tle valve into the steam chest; from the steam chest 
it passes through the high-pressure steam valve, 
through the steam port into the high-pressure cyl- 
inder. It forces the piston to the end of its stroke 
and then exhausts into the intermediate steam 
chest or into the receiver. From here it passes 
through the intermediate slide valve and steam 
port into the intermediate cylinder, expands and 
drives the piston to the end of the cylinder and 
exhausts into the low pressure steam chest where 
it drives the piston over by its expansion and ex- 
pands into the condenser. It is there condensed 
and passes the foot valve into the air-pump, and 
then through the air-pump bucket valve and head 
valve into the hot well. If a surface condenser is 
used, the condensed steam is pumped by the feed 
pump through the feed pipe and relief valve 
through a feed water heater and through another 
length of feed pipe past the check valve into the 
boiler. 

Q. What is a gusset stay, and where is it used in 
a boiler ? 

A. It is a stay made of iron plate which is 
carried from the front or back of the boiler to the 
boiler shell ; it is secured at each end by means of. 
angle irons and rivets. 



174 QUESTIONS AND ANSWERS FOR 

Q. What is double riveting, and in what parts 
of the boiler is it used ? 

A. Double riveting consists of two rows of rivets 
placed either zigzag or opposite each other ; the 
curvilinear seams are double riveted as well as the 
longitudinal seams in the furnace chamber and 
the horizontal seams of the ends. 

Q. What is calking, and how is it done? 

A. Calking means the closing up of the seams 
of boilers or iron vessels so as to make them 
steam- or water-tight. After the edges have been 
placed true and the plates riveted together, the 
edges are calked by a hammer and chisel, the 
iron being struck with the chisel in such a way as 
to close the joint. 

Q. Describe as many different methods as you 
know of fastening the ends of the mainstays of 
the boiler, and state their relative merits. 

A. First : Forked eye-bolts are tapped into the 
ends of the boiler and secured to them by a nut: the 
stay is secured at each end to them by a wrought 
iron pin and cotter, which prevents the pin from 
drawing back ; this form is very convenient, as by 
driving out the end pins the stays can be gotten 
out of the way in a few moments. Second : The 
end is made larger than the body of the stay and 
is threaded ; it is then secured to the boiler by nuts 
and washers inside and out. This arrangement 



STEAM ENGINEERS AND ELECTRICIANS. 175 

is mechanically good, but is somewhat difficult to 
remove. Third: The ends of the stay are made 
with a " T " head and are fastened between a pair 
of angle irons with rivets and bolts. 

Q. What is a rivet stay, and where are such 
stays commonly used ? 

A. A rivet stay consists of a long rivet passing 
through a thimble, or distance piece of iron which 
is placed between the plates to be stayed together. 
The ends of the rivets are then headed over in the 
usual way. The more common plan, however, is 
to tap both plates and thread the rivet, screwing the 
rivet through both plates and afterward heading 
the ends of the rivet over, which does away with 
the necessity of using the thimble. 

Q. Where do boiler tubes generally leak, what 
are some of the causes, and how is the trouble 
repaired ? 

A. Tubes usually leak at the combustion cham- 
ber end. Leaks are caused by allowing the 
plates and ends of the tubes to become foul, 
in which case they are liable to be overheated; 
another cause is blowing off of boilers under 
steam pressure. The trouble may be repaired 
usually by expanding the tubes. When they are 
much worn they should be driven in slightly from 
the smoke box end and re-expanded and rebeaded. 

Q. Where do the tube sheets usually crack? 



176 QUESTIONS AND ANSWERS FOR 

What are the reasons, and what methods are em- 
ployed for repairing ? 

A. The tube sheets generally crack in between 
the tubes. The cracks are caused sometimes by 
allowing scale to collect on the inside of the 
sheet or by the opening of furnace doors, which 
allows a current of cold air to strike the heated 
metal and produces contractions of the plates. 
One method of repairing is to cut a hole in a plate 
large enough to encircle the tube nearest the crack, 
fastening this small plate on to the boiler sheet 
so as to cover the crack. 

Q. What part of a marine tubular boiler is the 
first to be injured by low water? 

A. The top of the combustion chamber. 

Q. Why are blow-off cocks fitted to each boiler, 
and how many are usually supplied ? 

A. The blow-off cock is fitted to the bottom of 
the boiler shell, so that all deposit can be blown 
out of the boiler at its lowest point. One blow-off 
cock is fitted to each boiler, and is connected by 
pipe to a cock or valve in the ship's bottom. 

Q. At what heights are water gauge cocks 
placed, and must the cocks themselves necessarily 
be placed at these heights? 

A. There are usually three cocks, one of which 
is placed at a height of about 3 inches above the top 
of the combustion chamber; the next one at the 



STEAM ENGINEERS AND ELECTRICIANS. 177 

working water level, and the third in the steam 
space. It is not absolutely necessary that the 
cocks themselves should be placed at this level; 
they may be placed at any desired position, pro- 
vided that a pipe extends from each of them into 
the boiler, having its open end at the heights given 
above. 

Q. In a dead weight safety valve, how would 
you calculate the weight required ? 

A. The weight is equal to the area of the valve 
employed by the pressure of pounds per square 
inch at which the valve is to blow off. 

Q. Of what should the rubbing surface of safety 
valves be ? 

A. Of brass, gun metal, or nickel, so that 
they will not corrode and stick. 

Q. Explain in detail the construction of the 
glass water gauge and how it acts. To what de- 
rangements is it liable, and how are these repaired ? 

A. A water gauge consists of a long glass tube 
fixed in a brass stuffing box at each end; these 
stuffing boxes are usually connected together by 
brass columns, and the whole arrangement is 
attached to the boiler shell, the stuffing boxes 
having an opening into the boiler controlled by a 
valve whose stem is threaded into the boiler shell. 
The lower stuffing box also has a drain cock for 
blowing out the glass. The purpose of the gauge 
12 



178 QUESTIONS AND ANSWERS FOR 

is to show the level of the water in the boiler, and 
as its bottom is in connection with the water 
space and its top with the steam space, the water 
will rise in the tube to the same height in the 
boiler. The principal derangements are the 
breaking of the glass and choking up with im- 
purities. When the glass breaks, the two cocks 
which are connected with the boiler are clos"<], 
and a new glass is put in. If it becomes choked up 
with dirt, it may be cleaned by opening the drain 
cock and allowing the steam and water to rush 
through the glass. 

Q. You will sometimes see water gauges with 
pipe connections to the top and bottom instead of 
with a direct connection into the boiler ; what is 
this arrangement, and what is its advantage ? 

A. One pipe runs to the steam dome and the 
other to the bottom part of the boiler; the object 
being to prevent, so far as possible, certain dis- 
turbances in the water level in the glass, which, 
with the original arrangement, might be caused 
by priming or by the boiling of the water. 

Q. Why do some steam gauges have an inverted 
syphon pipe below them ? 

A. The syphon contains water whose object is 
to prevent the heat of the steam from injuring the 
machinery of the gauge. 

Q. W T hen the syphon is used, why is a small 



STEAM ENGINEERS AND ELECTRICIANS. 179 

cock put on the pipe leading to the steam 
gauge ? 

A. This cock is a drain cock on the boiler side 
of the syphon, placed at a level equal to the 
highest point to which water can rise in the other 
leg. Without this cock the indicated pressure will 
be too high, owing to the weight of the water which 
would collect in the boiler leg of the syphon. 

Q. What is meant by the salting of a boiler, 
and how is it prevented? 

A. Salting means allowing the water in the 
boiler to become very dense. It is prevented by 
occasionally blowing off a portion of the water in 
the boiler and taking in water which is less 
saline. 

Q. What is the difference between the formation 
of scale and salting of the boiler ? 

A. Salting is the gradual increase in the density 
of the water owing to the salt being left behind 
when the water is turned into steam, whereas 
scale is the deposit of insoluble substances like 
lime and magnesia on the heating surface. 

Q. What is the density of ordinary sea water, 
and how is it ascertained ? 

A. About one part of salt to 33 parts of water, 
or about 5 ounces per gallon. The density is as- 
certained by a salinometer, which consists of a 
float and graduated stem. 



180 QUESTIONS AND ANSWERS FOR 

Q. At what density should boilers be worked ? 

A. In general, at a density not exceeding ^3, 
or 10 ounces of salt per gallon. 

Q. What are scum cocks, and how are they ar- 
ranged and used ? 

A. Scum cocks are cocks placed on the shells of 
the boiler and connected to a pipe leading to the 
ship's side on which a cock is placed. From the 
cock on the boiler shell pipes lead into the boiler 
and are fitted on the end with a dish or trough 
slightly below the ordinary water line. The. scum 
cocks are used to remove dirt floating on the water 
surface and also a portion of the salt which is 
carried up b}' the steam bubbles to the surface. 

Q. What is boiler scale, and what bad effects 
does it produce ? 

A. Scale is produced by deposition of the im- 
purities contained in feed- water, and usually con- 
sists of a mixture of magnesia and lime salts and 
some common salt. It naturally collects at the 
hottest part of the boiler and causes the plates to 
burn, tubes to leak, and also diminishes the effi- 
ciency of the boiler. 

Q. Explain how the formation of scale can be 
best prevented and how it is removed from the 
boiler. 

A. It is prevented best by never wasting any 
steam or water in vessels which have a surface 



STEAM ENGINEERS AND ELECTRICIANS. 181 

condenser. With a jet condenser frequent blow- 
ing off is employed to prevent it. When scale is 
accumulated it is removed by chipping it off with 
hammers or a long chisel. 

Q. Explain how you would proceed to stop a 
leak from a split tube. 

A. I would close the ashpit doors and drive 
into the tube a plug of soft wood at each end of 
the tube ; the plugs will swell up owing to the 
moisture, and the tube will fill up with solid sub- 
stances which will stop the leak. 

Q. Describe the piston of a steam cylinder. 

A. The piston usually consists of a cast-iron 
disc stiffened with strong ribs. The disc is turned 
to an accurate circle on its outer edge, having 
grooves in it to receive the piston rings. The pis- 
ton rings are made with a slight opening and 
spring so that they press out against the cylinder 
surface and make a steam ij&pe joint. 

Q. For what are cylinder drain cocks used, and 
why is a valve sometimes placed on them ? 

A. Drain cocks are used for blowing out any 
water that may collect in the cylinders through con- 
densation or on account of priming. In the case of 
condensing engines a valve is fitted to them which 
opens outward only, the object being to allow the 
w r ater to be blown without permitting any air to 
rush in which would impair the vacuum. 



182 QUESTIONS AND ANSWERS FOR 

Q. Explain how a cylinder escape valve is made, 
and for what it is used. 

A. A cylinder escape valve consists of the valve 
seat and valve, the latter being loaded with the 
spiral spring. The amount of load is regulated 
by means of a screw which passes through the 
valve cover and presses on the disc which fits on 
the top of the spring. The object of the valve is 
to form a self-acting relief which will allow any 
sudden accumulation of water from priming or 
other cause to pass out of the cylinder without 
damage. These valves are covered with guards or 
domes with an escape pipe, so that the hot water, 
which is ejected from them, may not be thrown 
over the attendant. 

Q. What is the object of using multiple expan- 
sion engines? 

A. In order to obtain a greater economy in 
coal consumption. Other things being equal, the 
economy depends upon the difference between the 
temperature at which steam is taken into the 
cylinder and that at which it is exhausted. Since 
the lowest possible temperature is that corre- 
sponding to the absolute vacuum, it is obvious 
that in order to make the difference of tempera- 
ture great, we must admit the steam at a high 
pressure; but if the steam underwent its entire 
expansion in a single cylinder there would be a 



STEAM ENGINEERS AND ELECTRICIANS. 183 

great deal of condensation in the cylinder, since 
the incoming high pressure steam would come 
in contact with comparatively cold walls ; the 
expansion is therefore divided between two or 
more cylinders. A further advantage of having 
several cylinders is that the cranks are placed at 
an angle to each other, and more uniform turning 
moment is secured. 

Q. When engines are to be stopped with steam 
up, what would you close and what open ? 

A. I would close the throttle valve and the sea 
injection valve, and unless I were sure that the 
check valves on the boilers were tight, I would 
shut the feed so that no water would be lost from 
the boilers by blowing through the check valves. 
I would also close the damper doors; it might be 
advisable also to open the safety valve. 

Q. What would you do before starting ? 

A. I would open the drain cocks and blow 
steam through the cylinders and condenser so as 
to gradually warm them up. I would examine 
the valves to see that the proper ones were opened, 
as, for example, the feed check valves, the injec- 
tion and discharg3 valves, and would then gradu- 
ally turn the engine around. 

Q. What is the racing of an engine, and what 
danger is attached to it ? What can be done to 
prevent it ? 



184 QUESTIONS AND ANSWERS FOR 

A. The racing of an engine is the revolution of 
the engine at a very rapid rate, and is caused by the 
propellor coming out of water owing to the pitch- 
ing of the ship. The racing causes sudden and 
heavy strains on the machinery, such as may cause 
a breakdown, unless the most careful attention 
is given by the engineer. A governor is often 
fitted to the engines. In any case I would pro- 
ceed under easy steam and should cut down the 
supply of injection water. 

Q. What kind of a governor is employed ? 

A. A centrifugal governor. 

Q. With a surface condenser, what valves should 
be open some time before starting an engine ? 

A. The main stop valve and the main check 
valves to the boiler, the sea inlet for the circu- 
lating water, and all drain cocks on the cylinders 
and jackets. The discharge valves should be ex- 
amined to see if they are free to lift. 

Q. What is a steam jacket, and wh}^ is it 
used? With what engines are they generally 
found ? 

A. The steam jacket is a casing around a cylin- 
der, leaving a hollow space between it and the 
cylinder, which is kept supplied with steam from 
the boiler. The object of a steam jacket is to 
prevent, as far as possible, condensation in the 
cylinder. Jackets are generally found with multi- 



STEAM ENGINEERS AND ELECTRICIANS. 185 

pie expansion engines. They are covered with felt 
or some other non-conductor to prevent the radia- 
tion of heat. 

Q. What cocks are found on steam jackets, and 
why ? 

A. The steam jacket is supplied with a steam 
cock for turning on and shutting off steam from 
the boiler, and also with drain cocks, so that any 
accumulation of water in the jacket may be blown 
off into the hot well. 

Q. Name the principal j^ipes used with the en- 
gines and boilers of a steamer, and tell to what 
the ends of the pipes are connected. 

A. The main steam pipe connecting the stop 
valve on the boiler to the steam chest on the 
engine. Donkey steam pipe connecting the donkey 
stop valve of the boiler to the donkey steam 
chest. Cylinder jacket pipe running from the 
boiler to the jacket of the cylinder. Steam whistle 
pipe, pipes for any engines, or winches on deck ; a 
feed pipe connecting boiler with the feed pumps. 
Circulating water pipe connecting the inlet on the 
vessel's side with the circulating pump; feed suc- 
tion pipes connecting suction of the pumps and 
the hot well. A pipe connecting the air pump 
discharges with a valve on the ship's side and the 
hot well. Cylinder drain pipes connected to the 
drain cocks and the hot well ; blow-off and scum 



186 QUESTIONS AND ANSWERS FOR 

pipes connecting the cocks on the boiler to cocks 
on the ship's side. 

Q. Trace the passage of the circulating water for 
the surface condenser through the valves and pipes 
that it passes. 

A. The water is taken from the sea through a 
valve on the ship's side, passes through or around 
the condenser tubes to the foot valve of the circu- 
lating pump, then through the pump, cylinder, 
and head valve, and back through the discharge 
valve on the ship's side. 

Q. What is the path of steam from the boiler 
until it gets back to the hot well ? 

A. It passes through the main valve on the 
boiler, the main steam pipe and separator, if any, 
the throttle valve, valve chest, through the cylinder 
or cylinders, through the exhaust pipe into the sur- 
face condenser, and then falls to the bottom of the 
condenser in the form of water ; from there it is 
taken from the air pump and discharged into the 
hot well. 

Q. What is atmospheric pressure, how is it 
measured, and what is its average value ? 

A. Atmospheric pressure is the pressure due to 
the weight of the air. It varies with the height 
above sea level, having a value of about 14.7 
pounds«at sea level and growing less as the height in- 
creases. It is measured by means of the barometer. 



STEAM ENGINEERS AND ELECTRICIANS. 187 

Q. What is absolute pressure, and is absolute 
pressure shown by the steam gauge ? 

A. Absolute pressure is the pressure above a 
perfect vacuum. The steam gauge which under 
the pressure of the atmosphere only reads zero 
does not measure the absolute pressure in the 
boiler. To obtain the absolute pressure it is nec- 
essary to add the atmospheric pressure (about 
14.7 pounds) to the reading of the steam gauge. 

Q. What is a barometer, and for what is it used ? 

A. A barometer is an instrument consisting of 
a glass tube, sealed at its upper end, properly 
graduated and partially 'filled with mercury. It is 
inverted with its lower end immersed in a vessel of 
mercury. It is employed to measure the pressure 
of the atmosphere ; the greater the pressure of the 
atmosphere the higher does the column of mercury 
stand in the tube. 

Q. Can a barometer be used instead of a vacuum 
gauge ? 

A. Yes ; the top of the tube being connected 
to the condenser instead of being sealed up. 
The height of the column then indicates vacuum 
in the condenser instead of atmospheric pressure. 

Q. Are the indications of both steam and vacuum 
varied by changes in the barometer, and if so, why ? 

A. Yes ; if, for example, the reading of the 
barometer changes from 29 to 31 inches this would 



188 QUESTIONS AND ANSWERS FOR 

correspond to a change in atmospheric pressure of 
one pound, so that the steam gauge will read one 
pound too little and the vacuum gauge one pound 
too much, since the position of the needle de- 
pends upon the difference between the pressure to 
be measured and the atmospheric pressure. 

Q. When the reading of the vacuum gauge is 
20 inches, what will be the vacuum in the con- 
denser? Explain how you arrive at this result. 

A. 20 inches corresponds to a pressure of 10 
pounds, and this is the difference in pressure be- 
tween the atmosphere and the pressure in the 
condenser ; since the pressure of the atmosphere 
is 14.7, the pressure in the condenser will be 14.7 
minus 10, or 4.7 pounds, 

Q. Explain the construction of the thermometer, 
and state for what it is used. 

A. A thermometer usually consists of a small 
glass bulb communicating with a fine glass tube ; 
air is exhausted from the tube which is partially 
filled with mercury. When it is exposed to heat the 
mercury expands and rises in the tube, which is 
graduated. In the English or Fahr. scale the 
position at which the mercury stands when sur- 
rounded by melting ice is marked 32; when im- 
mersed in boiling water it is marked 212. The 
intervening space between these two marks is 
divided into 182 equal parts, called degrees. 



STEAM ENGINEERS AND ELECTRICIANS 189 

Q. A water ballast donkey pump has a diam- 
eter of 7" stroke of 15" and is double acting, 
making 120 revolutions per minute. The cylin- 
der is one-third empty each stroke. How long 
will it take to pump out 125 tons ? 

A. The quantity of water pumped per stroke is 
7 X 3i X V 5 cubic inches, or 110 cubic 
inches. -7 1 x,7rs-4x jo m 3&4,s< cuins. 

The quantity per minute is 110 X 240, or 

26,400 cubic inches. 
125 tons = 125 X 2000 pounds. 
125 X 2000 -=- 62| or 4000 = number of 

cubic feet in 125 tons. 
4000 X 1728 -4- 26,400 = number of min- 
utes required = 26 If f . (Ans. ) 
Q. A coal bunker 6' 9" wide at the top and 
5' 3" at the bottom has a length of 20' 3" and is 
8' high ; how many tons of coal will it contain ? 
A. The mean width is one-half 6' 9" -f 5' 3", 
or 6 feet. 
The cubic contents are 6 X 8 X 20J, or 972 

cubic feet. 

At 40 cubic feet per ton the number of tons 

will be 972 ~- 40 = 24JJ, or 24^- tons. 

Q. What will be the cost in dollars of a sheet 

of lead 12' 9" long by 8' 4" broad by J" thick, 

at 9 cents per pound, the weight of a cubic foot of 

lead being 691^ pounds ? 



190 QUESTIONS AND ANSWERS FOR 

A. 12' 9" = 153" ; 8' 4" = 100". The num- 
ber of cubic inches is 153 X 100 X J, or 

3825 cubic inches. 
The weight of a cubic inch of lead is 

691 T 2 o- -*- 1728, or T \ pound. 
The total weight of the lead is 3825 X tc> 

or 1520 pounds. 
The cost is 1520 X 9 cents, or 13,680 cents 
= 136^ dollars. (Ans.) 
Q. A spring-loaded safety valve has a waste 
pipe 20 feet high. If it became filled with water, 
what extra pressure would be on the valve ? 

A. y 4 oVo pound is the pressure due to 1 foot, 

20 feet will cause -&\\ X 20, or 8 ^V 

pounds pressure. (Ans. ) 

Q. A tank 2' 3" high, 2' 6" wide, and 3' 9" 

long has 90 gallons of oil in it ; how far from the 

top is the oil ? 

A. 2' 3" = 27"; 2' 6" == 30"; 3' 9" = 45". 
90 X 231 = 20,790 = number of cubic 

inches in 90 gallons. 
45 X 30 = 1350 = number of square 

inches in bottom of tank. 
20,790 -r- 1350 = 15^, the number of 

inches the oil will rise in the tank. 
30 — 153% 4 5- = 14^-? tne number of inches 
the oil is from the top. 



STEAM ENGINEERS AND ELECTRICIANS. 191 

Q. Subtract 1' 2|" from 2' 2f" and multiply 
remainder by 8. 

A. 2' 2f" = 2' 2f" 11£" 

1' W 8 

llf". 95". (Ans.) 

Q. If there are two bunkers each 5' 6" wide by 
14' 3" high, what length must they have so as to 
contain 80 tons of coal? State how many cubic 
feet you allow per ton. 

A. 5^ X 14J- = 78f = number of square feet 
in each. 
2 X 78f = 156f = number of square feet 

in both, 
At 40 cubic feet per ton, 80 tons will occupy 

3200 cubic feet. 
3200 -*■ 156f = 20' 3 T y nearly. (Ans. ) 
Q. Add together the following : 18' 3J"; 3' 
9J"; 14'; 3' 7^"; 
A. 



ft . 


9 5 n. 7' Q 9 " 


IS' 


3 1 " = 18' 33V 


3' 
14' 


9i"= 3' 9if " 
= 14' 


3' 

I 


7 7" Q' 71 4'/ 

'16 ° '32 

9 5// 90 // 

^3T ^3T 

3A" = V 3 T V' 



47' Iff" = 47' 1 f ". 

Q. How many tons will be contained in a bun- 
ker 25' long, 18' 6" high, having a width at the 
bottom of 19' and at the top of 21' ? 



192 QUESTIONS AND ANSWERS FOR 

A. The mean width is 20 feet. The cubic con- 
tents will be 20 X 25 X 18J, or 9250 
cubic feet. 
At 40 cubic feet per ton the number of tons 
will be 9250 -f- 40, or 231 \ tons. (Ans.) 
Q. The broadest part of the coupling bolt has 
a diameter of 3fV, the diameter of the narrow- 
est part is 2-J", the length is 7J"; what is the 
taper per foot ? 

A Q3" 07" 5 f 

Ji.. Oyg- L% yg- . 

T 5 g -J- 1\ = the taper per inch. 
■£$ X 12 -T- 7J = the taper per foot. 
T V X 12 = '«. or - 1 /. 

7 } = % V -s- fi = M of on e inch, or a 
little over J". (Ans. ) 
Q. What is f of ^ ? 

^ T 2 2V 

QUESTIONS FOR FIRST ASSISTANT ENGINEERS. 

[In addition to these the candidate should be prepared 
to answer the questions for third and second assistant engi- 
neers.] 

Q. Suppose you were put in charge of the 
engines of a boat you were never on before and that 
you had a day' s time before starting, what would 
you do on going into the engine room ? 

A. I would trace all pipes and connections 
to find out whence they come and where they 



STEAM ENGINEERS AND ELECTRICIANS. 193 

lead, and would examine all the cocks and valves 
in these connections ; I would then examine the 
boiler, carefully taking off all the doors and going 
inside to examine the stays and their fastenings 
and the tubes and flues, taking a hammer with 
me to sound the boiler plates ; I would then take 
the furnace bars out and the bridge down and go 
into the combustion chamber so as to examine 
carefully the ends of the tubes ; I would then 
inspect all the valves and cocks on the boiler ; next 
I would examine the engines, looking at the 
piston and valve gear and at all parts where there 
is any friction ; I would then examine the con- 
denser and the valves of all pumps ; finally, I 
would examine the shaft and its bearings and the 
stuffing box. 

Q. Explain in detail what occurs to coal when 
it is burned in a boiler, tracing its passage from 
the furnace door to the stack. 

A. Coal is thrown through furnace doors on the 
fire ; the heat of the fire liberates the hydrogen 
and hydrocarbon gases from the coal, and this as 
well as the pure carbon mixes with the oxygen 
that is contained in the air coming up through the 
grate bars ; these mixed gases burst into flame in 
the furnace and the products of combustion pass 
through the tubes and flues, giving up a large 
amount of their heat to the water in the boiler ; 

13 



194 QUESTIONS AND ANSWERS FOR 

the products of combustion then pass into the 
up-take and funnel and escape to the outside air. 

Q. Where would you expect to find thin plates 
in a boiler, and how would you detect the thin- 
ness ? 

A. Plates usually become thin by wear in the 
ashpits, at the back of the combustion chamber, 
in the shell at the water line, and a. little above 
the line of the fire bars in the furnace. A thin 
plate can be detected generally by sounding with 
a hammer ; small holes can also be drilled at any 
part that is suspected and of course afterward 
plugged up. 

Q. How are boiler tubes l ' fixed ? ' ' 

A. They are driven from the smoke box end 
through both tube plates until they project a little 
over J of an inch into the combustion chamber 
and remain about J inch outside of the tube plate 
at the smoke box end ; the tubes are then 
expanded either by tapered drift or by a tube 
expander. The ends of the tubes in the combus- 
tion chamber are then beaded over, while those 
at the other end are sometimes left without bead- 
ing, so that in case of leakage the tubes may be 
driven in and beaded again. 

Q. What is a superheater, and how is it con- 
structed ? 

A. A superheater is an apparatus placed in the 



STEAM ENGINEERS AND ELECTRICIANS. 195 

up-take or at the base of the funnel, so arranged 
that the products of combustion pass around and 
through it before they escape up the chim- 
ney. Its purpose is to impart an additional 
amount of heat to the steam from the boiler 
before it passes to the engine. A simple form of 
superheater consists of a wrought-iron drum built 
with tubes ; the products of combustion pass 
through the tubes and around the shell, the steam 
being inside the drum. 

Q. What fittings should a superheater have ? 

A. It should have a valve for cutting off steam 
connection from the boiler and also from the 
engine. It should also have a by-pass, so that the 
superheater may be thrown out of action. It also 
requires a safety valve and a gauge glass, the lat- 
ter being for the purpose of showing whether the 
superheater is clear of water, as excessive priming 
may sometimes fill it. 

Q. What causes a draught in a funnel ? 

A. The difference in weight between the hot 
gases in the funnel and the weight of a column of 
external air of the same volume. 

Q. The draught is sometimes checked, — what is - 
the cause of it? What symptoms would you 
notice, and how would you remedy the trouble? 

A. The draught is sometimes checked by a down- 
ward current of air meeting the upward rush of hot 



196 QUESTIONS AND ANSWERS FOR 

air as it ascends the chimney, the action being ac- 
companied by a buzzing noise. This down draught 
is the result of the admission through the furnace of 
too small a quantity of air to supply the exhaust, 
due to the ascending column of hot air in the fun- 
nel ; the down draught can therefore be stopped 
by partially closing the damper and opening the 
fire doors. 

Q. What parts of a steam plant should be cov- 
ered with non-conducting covering, and why ? 

A. The boiler, the up-takes, base of the funnel, 
all steam pipes, the cylinders, the heaters, separa- 
tors, and, in general, all apparatus that has steam 
inside of it. The object of a covering is to pre- 
vent, so far as possible, the radiation of heat. 
Such radiation would not only make the boiler 
and engine room excessively hot, but would also 
result in the waste of fuel. 

Q. What substances are used for making non- 
conducting coverings ? 

A. Asbestos, hair felt, mineral wool, and mag- 
nesia are the most common. 

Q. Do steam gauges indicate the total pressure 
of the steam ? 

A. Steam gauges indicate the pressure of 
steam above the atmosphere only, and their indi- 
cations are therefore about 14.7 pounds below the 
value of the total pressure. 



STEAM ENGINEERS AND ELECTRICIANS. 197 

Q. For what purpose is a salinometer used, and 
how is it constructed ? 

A. A salinometer is an instrument used to 
find out the density of water. It consists of a 
weighted bulb attached to a graduated stem. 

Q. Explain the action of the salinometer and 
how it is graduated to read. 

A. The salinometer indicates the amount of 
salt or other matter held in solution in the water 
by the depth to which it sinks. The fresher the 
water, the lower it will sink. It is graduated in 
32ds, each 32d representing about 5 ounces of 
salt per gallon of water. 

Q. What is necessary in order that the sali- 
nometer give correct indications ? 

A. It must be used at the temperature at which 
it is marked. 

Q. Suppose that the check valve of one of a 
set of boilers should have a piece broken off the 
valve, what trouble would this cause, and what 
would you do to remedy it ? 

A. The boiler whose check valve is broken 
would get more than the proper amount of the 
feed water, while the other boilers would have a 
great difficulty in getting sufficient amount. To 
remedy this, I would close the broken valve par- 
tially and, if possible, would open up the other 
valves more than before. 



198 QUESTIONS AND ANSWERS FOR 

Q. In modern marine engines, when a link 
motion is not used, what takes its place ? 

A. Some patent valve gear, such as Joy's. 

Q. What causes the friction on a slide valve, 
and how can the amount of this friction be re- 
duced ? 

A. The friction is caused by the action of the 
steam on the unbalanced area of the slide valve, 
pressing it against the valve seat with a force that 
is equal to this area multiplied by the steam pres- 
sure. This friction can be diminished by reliev- 
ing the back of the valve from the steam pressure; 
this is accomplished by forming a vacuum or ex- 
haust steam pressure space at their backs by 
means of a brass packing held up to the valve 
with springs or india-rubber. This space is put 
into communication with the condenser or exhaust, 
and therefore a pressure equal to the vacuum 
tends to lift the valve from its seat. 

Q. Explain how you could measure the travel 
of the eccentric rod. 

A. The travel of the eccentric rod is the dis- 
tance moved by the rod on the up or down-stroke. 
If the sheave be off, the travel can be measured 
by measuring the distance between the shaft 
opening and the center of the eccentric disc ; 
this multiplied by 2 will give the travel of the 
rod. If the sheave cannot be conveniently taken 



STEAM ENGINEERS AND ELECTRICIANS. 199 

off the shaft the travel can be measured in this 
way: Subtract the width, of the thickest part of 
the sheave from the broadest part, and the re- 
mainder will be the full travel. 

Q. Explain the construction of the surface 
condenser. 

A. A surface condenser consists of an iron box 
containing a large number of tubes ; these tubes 
may be either horizontal or vertical, and are 
made of brass. At each end of the tubes are 
tube plates through which the tubes pass, — there 
is often a supporting plate in the middle. At 
each end of the condensers are doors or openings, 
so that the ends of the tubes may be examined or 
repaired when necessary. In some cases steam is 
admitted to the tubes, and the injection water 
passes around the outside of the tubes; in other 
cases steam is led into the space around the tubes, 
and water passes through them, the latter practice 
being the more general. 

Q. Suppose that a tube splits, what would you 
do? 

A. I would drive in a wooden plug at each end, 
and keep it there until I had an opportunity of 
taking out the tube and replacing it with a new 
one. 

Q. Where do surface condensers become foul, 
and how are they cleaned? 



* 



200 QUESTIONS AND ANSWERS FOR 

A. Surface condensers become foul both on the 
inside and outside of tubes. The outside of the 
tube has a deposit owing to. the salt water ; the 
steam side of the tube fouls owing to the action 
of the grease and oil that are in the steam coming 
from the cylinders. The condensers are cleaned 1 1 y 
scalding them with hot water taken from the boiler 
with a hose. Caustic soda is also generally used. 

Q. What is a vacuum, and with what appar- 
atus is it produced ? 

A. A vacuum is a space devoid of pressure. It 
is impossible to produce a perfect vacuum, but a 
partial vacuum is produced by means of a con- 
denser and air pump. 

Q. Explain how you would proceed to produce 
a vacuum with a jet condenser. 

A. I would first open the blow-through valve, 
allowing the steam to blow out all air and water 
in the condenser and at the same time to warm 
the condenser up; as soon as steam issues from 
the snifting valve I would shut the blow-through 
valve and open the injection cocks ; the cold 
water will then mix with the steam, condense it 
and form a vacuum. As soon as the gauge shows 
a sufficient vacuum I would shut off the injection 
cocks, so as to prevent the condenser's filling. 

Q. Explain the method of operation if the 
condenser were of the surface type. 



STEAM ENGINEERS AND ELECTRICIANS. 201 

A. Some time before starting I would open the 
injection valve, so that the circulating water 
might enter the injection tubes and cool them ; 
then as soon as the engines are started the steam 
coming in contact with these cold tubes will be 
condensed, and after the first two or three turns 
of the engine the condenser will be clear. 

Q. How is the vacuum maintained ? 

A. By the constant condensation of the used 
steam by means of cold water or cold tubes and 
by constant clearing of the condenser by the air 
pump. 

Q. Why does the condensation of steam make 
a vacuum ? 

A. Because a cubic foot of steam when con- 
densed into the form of water occupies only about 
one cubic inch of space. 

Q. What is the advantage of a surface con- 
denser over the jet condenser? 

A. The injection water is not mixed with the 
water of condensation; the boilers are therefore at 
all times supplied with fresh water, thus prevent- 
ing the formation of scale, increasing the dura- 
bility of the boiler, and making a saving in the 
consumption of fuel. 

Q. Explain the meaning of the terms "injec- 
tion water ' ' and ■ ' water of condensation, ' ' 

A. " Injection water " is the water introduced 



202 QUESTIONS AND ANSWERS FOR 

into the condenser for the purpose of condensing 
the steam; " water of condensation" is the water 
resulting from the condensation of the steam itself. 

Q. About how much injection water is neces- 
sary to condense steam ? 

A. About twenty-five times the amount of the 
water of condensation. 

Q. Has the air pump as much duty to perform 
in the case of surface condensers as with jet con- 
densers ? 

A. No ; with surface condensers the air pump 
has only to extract the air and the water of con- 
densation ; in the case of the jet condensers it has 
not only to extract this, but also the injection 
water. 

Q. How is the amount of vacuum in the con- 
denser determined ? 

A. By the vacuum gauge. 

Q. What is the meaning of " a reading of 16 
inches on the vacuum gauge ? ' ' 

A. Two inches of mercury corresponds closely 
to 1 pound of vacuum ; therefore 16 inches of 
mercury represents 8 pounds vacuum, — that is to 
say, a pressure 8 pounds less than atmospheric 
pressure, or a pressure of about 6. 7 pounds abso- 
lute. 

Q. What is a circulating pump ? For what pur- 
pose is it used, and how is it driven ? 



STEAM ENGINEERS AND ELECTRICIANS. 203 

A. A circulating pump is one used to cause 
water from the sea inlet to circulate through the 
condenser tubes; it is operated sometimes by a 
lever connected to the main engine, and in other 
cases by means of an independent engine. 

Q. Why is an air valve sometimes fitted to a 
circulating reciprocating pump ? 

A. So that the air will tend to obviate the solid 
resistance that would otherwise be offered by the 
water. 

Q. Explain the difference between a bucket air 
pump, a piston air pump, and a plunger air pump. 

A. A bucket air pump has a brass piston 
packed with a spun-yarn gasket to keep it tight ; 
the body of the bucket has perforations allowing 
water to pass through on the down stroke. The 
action of the pump is as follows : On the down 
stroke the water rushes through the perforations 
of the bucket, and as soon as the up-stroke be- 
gins the weight of the water forces down the 
india-rubber valve ; the bucket lifts the water up 
and discharges through the head valve the water 
that was taken in through the bucket on the 
down stroke ; at the same time a vacuum is cre- 
ated on the under side of the bucket, into which 
the condensed water and air flow from the con- 
denser ready to be taken by the bucket on the 
next down stroke. 



204 QUESTIONS AND ANSWERS FOR 

A piston air pump, usually a double-acting 
pump, has suction and delivery valves at both 
ends. The bucket in this case is solid, and the 
water is taken and forced out of the pump on 
both the outward and return strokes. 

A plunger air pump has a solid plunger or ram 
working through a bushing. 

Q. When the condenser is working and the air 
pump bucket is at the top of its stroke, at what 
height will the water stand in the condenser, as 
compared with the level of water in the air-pump 
chamber ? 

A. The comparative level in the two places de- 
pends upon the intensity of the vacuum existing 
in the two places, that in the chamber being 
always the best. If the vacuum in the pump 
were 29 inches and that in the condenser 28 
inches, the difference in vacuum would be 1 inch 
or \ pound, which corresponds to a difference in 
level of water of 1.1 feet, so that the level in the 
condenser would be that amount below the level 
in the pump. 

Q. With a surface condenser and single-acting 
air pump, what would be the effect of a leaky foot 
valve? What would be the effect of a leaky 
bucket if there is also a foot valve ? 

A. Provided the foot valve is sufficiently im- 
mersed in water, its leaking will not affect the 



STEAM ENGINEERS AND ELECTRICIANS. 205 

working of the pump ; the effect of a leak in the 
bucket depends upon whether the pump is work- 
ing to its full capacity. In ordinary cases the 
air pump never works anywhere nearly full of 
water. Suppose that the pump ought to lift, say, 
one gallon of water each stroke and by reason of 
the leak one-half gallon passed back, then the 
water would rise in the condenser high enough 
so that the bucket would lift one and one-half 
gallons; but as one-half would be allowed to pass 
back through the leak, the proper amount of one 
gallon would be actually left at each stroke. In 
case the pump were working at its full limit and 
the bucket were leaky, the condenser would grad- 
ually fill up. 

Q. What is the temperature at which water 
usually stands in the hot well ? What would be 
the effect of temperature lower or higher than 
this amount ? 

A. The temperature usually varies from 110 to 
130 degrees. A higher temperature than this is 
liable to cause a deterioration of valves, and a 
lower temperature will produce an increase in the 
consumption of fuel. 

Q. How could you tell whether the inlet valve 
of the circulating pump were open to the proper 
amount ? 

A. By the vacuum gauge and by the condenser. 



206 QUESTIONS AND ANSWERS FOR 

If the valve is open too little, the condenser will 
get hot and a low vacuum will result ; if the 
valve is too far open, the condenser will get too 
much water and will become cold, although the 
gauge will show a good vacuum. 

Q. What is the object of placing a pet cock or 
valve on the feed pump, and where should it 
be placed ? 

A. It should be placed above the suction valve 
of the pump ; it enables the engineer to see if the 
engine is working, and also it forms an air cushion 
which prevents heavy knocking in the pump. 

Q. How are the ends of surface condenser tubes 
fastened ? 

A. One method is to tap the holes in the tube 
sheet for a part of the thickness ; after the tube is 
put in place, a packing is inserted around it, and 
a brass ferrule is screwed in which forces the pack- 
ing up against the tube. Another method is to 
make use of a wood ferrule fitting around the tube 
which is driven into the tube plate. 

Q. What is a snifting valve, and where is it 
placed and what is its purpose ? 

A. A snifting valve is a small relief valve 
which is placed on the bottom of the condenser. 
It is arranged in such a way that the vacuum in 
the condenser keeps the valve closed, and in case 
of an excessive pressure in the condenser the 



STEAM ENGINEERS AND ELECTRICIANS. 207 

valve will open and relieve it. Such valves are 
not always used now, especially with compound 
engines, as the necessity of starting with a good 
vacuum is not so great as with simple engines. 

Q. What is cushioning in a steam cylinder? 
What produces it and what advantage is it? 
Does the amount of the exhaust pressure affect it ? 

A. Cushioning is caused in the cylinder by the 
closing of the exhaust before the piston has com- 
pleted its stroke. The advantage lies in the pro- 
duction of a sort of cushion owing to the elasticity 
of the compressed steam, which takes off from 
the piston the heavy knock that would otherwise 
take place at the end of a stroke. The amount 
of cushioning depends upon the exhaust lap and 
the back pressure, increasing if either of these are 
increased. 

Q. About what vacuum should the vacuum 
gauge show when the engines are working all right, 
and to what absolute pressure does this corre- 
spond ? 

A. About 27 inches. This corresponds to a 
pressure of about 13^ pounds below the atmos- 
phere, or about 1.2 pounds absolute. 

Q. What is the extreme height to which, theo- 
retically, water can be drawn by a suction pump, 
and how does this compare with the result 
obtained in practice ? 



208 QUESTIONS AND ANSWERS FOR 

A. The extreme vertical height is about 34 feet. 
In practice it is difficult to exceed 26 feet. 

Q. What is a vacuum ? Can it move a piston ? 

A. A vacuum is a space devoid of pressure. 
A vacuum cannot, strictly speaking, move a 
piston. It is the preponderance of the atmos- 
pheric pressure above that of the vacuum which 
moves the piston. 

Q. When the temperature of the water in the 
condenser is 212 degrees, what is the vacuum in 
the condenser? 

A. There is no vacuum in the condenser, be- 
cause the water will boil at that temperature and 
give off steam that will have a pressure equal 
to the atmospheric pressure. 

Q. What is the temperature of the following : 
(1) Melting ice ; (2) the hot well ; (3) boiling 
water ; (4) steam at 60 pounds gauge pressure ; 
(5) steam at 100 pounds ; (6) steam at 135 
pounds ; (7) the hot gases in the funnel? 

A. Melting ice, 32 degrees Fahr. ; hot well, 120 
degrees ; boiling water in open air, 212 degrees ; 
steam at 60 pounds, 307 degrees ; steam at 100 
pounds, 338 degrees ; steam at 135 pounds, 358 
degrees ; hot gases, from 600 to 700 degrees. 

Q. What are the effective heating surfaces in a 
marine boiler ? Are the vertical surfaces as effi- 
cient as horizontal ? 



STEAM ENGINEERS AND ELECTRICIANS. 209 

A. The effective heating surfaces of a marine 
boiler are those portions situated above the fire 
bars which are exposed to the heat of the flame 
and the products of combustion. Vertical sur- 
faces are much less efficient than horizontal. 

Q. In what ways could you ascertain the pres- 
sure in a steam boiler ? 

A. The ordinary method is, of course, by the read- 
ing of the steam gauge. If this were out of order an 
approximate determination of the pressure could be 
made by seeing at what position the safety valve 
would blow off. If neither of these were avail- 
able, a still rougher method would be to take a 
bottle containing a thermometer and blow off 
steam from one of the gauge cocks into the bottle. 
After the thermometer has reached its maximum 
reading I would find from tables what pressure 
of the steam corresponded with the temperature 
shown by the thermometer. 

Q. How could you test the trueness of the pro- 
peller shaft without lifting it ? 

A. I would slacken the coupling bolts and see 
if the distance between the edges of the couplings 
is the same all around ; I would stretch a line hor- 
izontally along the shaft and measure from it to 
the sides of the couplings ; if they are of the 
same diameter all the distances should be the 
same. 
14 



210 QUESTIONS AND ANSWERS FOR 

Q. Suppose the air-pump rod should break and 
you had no extra rod on board or nothing with 
which you could make one, what would you do ? 

A. The condenser ought to be arranged with a 
by-pass, so that by means of valves it could be 
shut off and the engine run non-condensing. If 
there is no by-pass, I would rig up a temporary 
exhaust pipe and run non-condensing. 

Q. Suppose that the cylinder head cracked or 
broke, what would you do ? 

A. I would endeavor to repair it with iron ; 
or, if I had no suitable pieces of iron, I would 
strengthen it with plank and ropes or wire ; if it 
was impossible to do this, I would, of course, 
draw my fires and let the boat go under sail. 

Q. Suppose the crank pin should break, what 
would you do ? 

A. I would remove it and replace it with a new 
one if there was one on board ; if not, it would be 
necessary to detach the propeller shaft and go 
under sail. 

Q. Suppose the cut-off mechanism should be 
broken at one end, what would you do ? 

A. If I could not readily repair it I would 
remove the mechanism from the other end also 
and would work the engines full stroke. 

Q. Examine the following indicator cards and 
state what faults they show in the engines. 



STEAM ENGINEERS AND ELECTRICIANS. 211 

A. See ''Roper's Engineers' Handy Book," 
pages 545-548. 




Diagram from simple slide valve engine, 16" x 30". 



Diagram from 18" x 36" engine with cut-off valve operated by Kendal 
Governor. 



212 QUESTIONS AND ANSWERS FOR 




Diagram from simple slide valve engine, 9" x 15". 




Diagram from same, 9" x 15" engine, with different valve setting. 



STEAM ENGINEERS AND ELECTRICIANS. 213 

Q. A certain surface is 14' 3f" long by 7' 1\" 
broad ; what is the area in square feet and deci- 
mals of a square foot ? 

A. 14' 3f" = 14.3125'; 7' 1J" = 7.125'. 
14.3125 X 7.125 = 101.9765625'. (Ans.) 

3 " ■= J' or .25' 
J" = .75" or .0625' 
3|" = .3125' 

li" = 1.5" or .125' 

14.3125 
7.125 

715625 
2862§0 

143125 

1001875 

101.9765625 

Q. An oil tank 3' long by 2' broad has a height 
of 3'. On Wednesday the height of the oil is 
noted in the glass gauge, and on the following 
Tuesday at the same hour the height is again 
noted, the difference in height being 8-J-"; what is 
the average consumption per day in gallons and 
decimals of a gallon ? 

A. 3 X 2 X 144, or 864 == area in square 
inches of floor of tank. 
The time from Wednesday to Tuesday is 6 



214 QUESTIONS AND ANSWERS FOR 

The number of cubic inches of oil used is 
864 X 8.5, or 7344. 

The number of gallons is 7344 -r- 231 and 
the number of gallons per day is one- 
sixth of this. 

6 )7344 
231)1224(5.299 nearly. (Ans.) 
1155 

690 
462 

2280 
2079 

201 

Q. How long will it take to pump out a tank 
30' by 20' 3" by 6' 4" ? The diameter of the 
pump, which is double acting, is 8" and its stroke 
is 10"; the pump makes 70 revolutions per min- 
ute ; the pump is -^ full at each stroke. 

A. The volume of the tank is 30 X 20J X 6J, 

or 3847.5 cubic feet. 

The amount of water per stroke is . 7854 X 

8X8X10X4 or 452. 39 cubic inches. 

The amount of water per minute is 452.39 

X 70 X 2 h- 1728, or 36.65 cubic feet. 
The number of minutes required is 3847.5 
-s- 36.65, or 104.98 minutes. (Ans.) 
Q. What is the approximate weight of a cast- 



STEAM ENGINEERS AND ELECTRICIANS. 215 

iron piston 18" diameter and 2" thick? What 

weight do you allow per cubic foot for the cast 

iron ? 

A. The volume of the piston is .7854 X 18 X 

18 X 2, or 508.9392 cubic inches. 

508.9392 -5- 1728 = the number of cubic 

feet. 

Allowing 450 pounds per cubic foot, the 

. , . .„ , 508.9392 X 450 1QO ro 
weight will be — , or 132.53. 

1728 

(Ans.) 

Q. A scale of iron rust which you have taken 

off weighs 10 ounces ; the composition of rust is 

112 parts by weight of iron to 48 parts oxygen ; 

how many ounces of iron was in this scale ? 

, ™ , . . H2 X 10 1120 

A. The amount of iron is = 

112 + 48 160 

= 7 ounces. (Ans. ) 

Q. Suppose that a bar of iron has a weight of 
one ton suspended on it, and it is found to stretch 
one inch in 12,000 ; what will be the stretch of a 
similar bar whose length is 20' if a weight of 10 
tons is suspended upon it ? 

A. With 10 tons suspended on it instead of 1 
ton, the bar would stretch 10 inches in 12,000, or 
x^oo of its length, ^m °^ 20 feet is -^nftj- of 1 
inch. T 2 ^o °f an ^ ncn == • 2 inch. (Ans. ) 



216 



QUESTIONS AND ANSWERS FOR 



Q. There are 275 tons of coal in the bunkers, 
the average percentage of ash being 15 ; how much 
actual fuel is there in the bunkers ? 

A. If the ash is 15 per cent., the actual amount 
of coal is 100 — 15, or 85 per cent. 

275 

.85 

1375 
2200 



233.75 tons. (Ans.) 

Q. What is the square of 271.6? What is the 
cube of 54.3? 



A. 



271.6 
271.6 

16296 

2716 
19012 
5432 

73766.56 (Ans.) 



54.3 
54.3 

1629 
2172 
2715 

2948.49 
54.3 

884547 
1179396 
1474245_ 

160103.007 (Ans.) 

Q. A tank in a steamer 20' 6" diameter by 22' 
3" deep is to be used for a coal bunker, but 
the bottom to the height of 4' cannot be used 
for coal ; how many tons of coal can be put in 



STEAM ENGINEERS AND ELECTRICIANS. 217 

the tank, and how long will it last if the average 
rate of consumption is 40 tons per day ? 

A. The area of the tank is. 7 854 X 20.5 X 20.5 
square feet. 
The space available for coal has a depth of 

22' 3" — 4' = 18' 3", or 18.25 feet. 
The volume in cubic feet is .7854 X 20.5 
X 20.5 X 18.25, or 6023.4125. 



.7854 


330.05 


20.5 


18.25 


39270 


165025 


15708 


66010 


16.10070 


264040 


20.5 


33005 


805 


6023.4125 


322 


40)6023.4125(150.5853 tons. 


330.05 


40 




202 




200 




234 




200 




341 




320 




212 




200 




125 




120 




5 



218 QUESTIONS AND ANSWERS FOR 



40)150.5853(3. 


7646 days. 


120 




305 




280 




258 




240 




185 




160 




253 




240 




13 




.7646 days 


.3524 hours 


24 


60 


30584 


21.1440 minutes. 


15294 




18.3524 hours. 


.144 minutes 




60 




8.640 seconds. 



Answer : The coal will last (assuming that a 
ton occupies a space of 40 cubic feet) 3 days, 18 
hours, 21 minutes, and 8.64 seconds. 

Q. What is the sum of -£% and -^ in deci- 
mals ? 

A. 2T = . 13636 

■& = . 36842 

.50478 (Ans.) 



STEAM ENGINEERS AND ELECTRICIANS. 219 

22)3. 00000(. 13636 19)7.00000(. 36842 

22 57 

80 130 

66 114 

140 160 

132 152 

80 80 

66 76 

140 40 

132 38 



Q. An engine after being compounded gener- 
ated 20 per cent, more power from the same 
amount of fuel (10 tons a day) ; how many tons 
of coal will be used if the engine be worked com- 
pounded at the original power? 

A. If we call the old power 100 per cent. , the 
new power will be 120 per cent. Then 120 : 100 
= 10 : number of tons which will be used. 

10 X 100 -- 120 = Si tons. (Ans.) 

Q. If the coal consumption is 30 tons a day, 
and if each of the six watches throws away 36 
baskets of ashes weighing 50 pounds each, what 
percentage of the fuel is ash ? 

A. 36 X 50 = 1800 pounds, the ash per day. 
2240 X 30 = 67,200, the total number of 
tons of fuel burned per day. 



220 QUESTIONS AND ANSWERS FOR 

67200)1800.000(.027 nearly. 
134400 

456000 

.027 = 2.7 percent, (Ans.) 

Q. A cylinder has a diameter of 30". The 
packing ring is too large and a piece -^ of an 
inch is cut out of it ; then when it is put in 
place there is an opening of -^ in the ring ; what 
is the difference between the diameter of the 
cylinder and diameter of the ring before it was 
cut? 

A. The circumference of the inside of the cyl- 
inder is 3.1416 X 30 = 94.248". 
-gV" = .03125". 
A" = .5625". 
94.248" — .03125" -f .5625" is the diameter 

of the ring before it was cut. 
Therefore the difference between the diame- 
ter of the cylinder and that of the ring is 
(94.248 — .03125 -f 5625) -94.248, or 
. 5625 — .03125 inch = . 53125". (Ans. ) 

Q. What is the horse-power of an engine 
whose cylinder is 36" in diameter, whose stroke 
is the same and which makes 40 revolutions per 
minute if the mean effective pressure is 40 
pounds ? 



STEAM ENGINEERS AND ELECTRICIANS. 221 

.7854 3 

36 40 



47124 120 

23562 40 



28.2744 4800 

36 2 



1696464 9600 

848232 



1017.8784 
1017.* 



9600 



61072800 
916092 



33000)9771648.00(296 horse-power. (Ans.) 
66000 
317164 
297000 
201648 
198000 
3648 
The area of the piston is .7854 X 36 X 36, 

or 1017.8784 square inches. 
The horse-power is equal to the area X fl 
X 40 X 2 X 40 -T- 33,000, or 296 horse- 
power. (Ans. ) 
Q. What is the proportion between the area of 
an 8" steam pipe and of a cylinder of 40" diam- 
eter? 



222 QUESTIONS AND ANSWERS FOR 

A. The areas are in proportion to the squares 
of the diameters and are therefore as 8 X 8 : 40 
X 40, or as 64 : 1600, or 1 : 25. 

Q. If the feed- water has 4J ounces of salt per 
gallon, and if you continuously blow off -J of the 
total feed, what will be the degree of saltness in 
the boiler ? 

A. £ = 62.5 per cent. 

62.5 : 100 : : 4.5 : Answer. 

4.5 X 100 n o i /a n 

— -£— — ■ = 7. 2 ounces per gal. ( Ans. ) 

Q. The blow-off cock on the bottom of a boiler 
is 13' below sea level ; the water level in the boiler 
is carried 9' above the blow-off cock ; how much 
pressure will be needed in the boiler to enable you 
to blow out water ? 

A. The water level in the boiler is below the 
sea level by an amount equal to 13 — 9, 
or 4 feet. 
4 feet corresponds to a pressure of .434 X 

4, or 1.736 pounds. 
Therefore a pressure a little greater than this 
will be needed in order to blow out. 

Q. If the feed-water has 4^- ounces of salt per 
gallon, and if you do not wish to exceed a salt- 
ness of 9J ounces in the boiler, what percentage 
of the feed-water must be blown off ? 



STEAM ENGINEERS AND ELECTRICIANS. 223 

A. 9.5 : 4.2 : : 100 : Answer. 

100 X 4.2 U2 t (Ans ) 

9.5 l 

REQUIREMENTS FOR ENGINEERS IN THE 
REVENUE MARINE. 

The requirements for engineers in the Revenue 
Marine are about the same as those for chief 
engineers in the Merchant Marine, as will be seen 
by comparing the following extract from the 
general orders of the treasury department with the 
corresponding paragraphs in the Frye Bill. On 
this account no questions and answers for candi- 
dates have been inserted. 

1. No person will be examined for, or commis- 
sioned a second assistant engineer in, said service 
who is not a citizen of the United States. 

2. Candidates must not be less than twenty- 
one nor more than twenty-eight years of age, and 
must be of vigorous constitution, physically sound 
and well formed, and not less than five feet three 
inches in height. 

The application for examination must be in the 
handwriting of the applicant and addressed to 
the Secretary of the Treasury. It must state the 
date and place of birth, and the State of which a 
resident. If the applicant be of foreign birth it 
must be shown that he is a citizen of the United 
States. 

3. The application must be accompanied with 
satisfactory evidence of the good moral character 



224 QUESTIONS AND ANSWERS FOR 

and correct habits of the applicant, and certificates 
showing his experience either in a machine shop 
or in charge of a steam engine in a technical insti- 
tution, or in the engine room of a steamer, as 
required by paragraph 5. 

4. Candidates will be required to pass a satis- 
factory examination as to their physical qualifica- 
tions before a board of medical officers to be desig- 
nated by the Secretary of the Treasury. The 
physical examination will precede the profes- 
sional, and should the candidate be found phys- 
ically disqualified he will be examined no further. 

5. To be eligible for examination a candidate 
must have had not less than eighteen months' ex- 
perience in a machine shop, or responsible charge 
of a steam engine for that length of time ; or, if a 
graduate of a technical institution, he must have 
had the full four years' course in mechanical 
engineering ; and in addition to either of the three 
preceding requirements, he must also have had 
not less than six months' experience in charge of, 
or assisting in, the care and management of the 
steam machinery of a sea-going vessel in actual 
service. 

6. Candidates having been found physically 
qualified will be examined professionally by a 
board of engineer officers of the Revenue Cutter 
Service, in the following subjects, the questions 
and answers all being written : 

(a) Grammar, spelling, punctuation, composi- 
tion, penmanship. 

(b) Statement of shop and engineering expe- 
riences and sea-service. 



STEAM ENGINEERS AND ELECTRICIANS. 225 

(c) Elementary mathematics, including arith- 
metic, algebra, geometry, trigonometry, and the 
use of logarithms. 

(d) Elementary mechanics and physics, in- 
cluding mechanical powers, friction, laws of fall- 
ing bodies, force, work, etc. 

(e) Practical problems connected with steam- 
engineering, such as calculation of loss by blowing 
off, gain by use of heaters, amount of condensing 
water required, safety valye problems, etc. 

(/) Incrustation and corrosion in marine 
boilers and problems connected with combustion. 

(g) Marine boilers, description of various 
types, with their advantages and disadvantages, 
repairs to same, practical management of boilers, 
and discussion of accidents and difficulties, such 
as foaming, back-draft, etc. 

(h) Heat, steam, theory of expansion, use of 
steam. 

(/') The steam-engine indicator, interpretation 
from diagrams therefrom, calculation of horse- 
power and evaporation from diagrams. 

( j) Marine engines — description of the various 
types including those used with paddle-wheels, 
with advantages and disadvantages, special atten- 
tion being given to multiple-expansion engines, 
practical questions relative to care and manipula- 
tion of engines, overhauling and repairs, align- 
ments, etc. 

(&) Valves and valve-gears as applied to marine 
engines, including those used on side-wheel 
steamers, but with special attention to modern 
types used with propeller engines. 

15 



226 QUESTIONS AND ANSWERS FOR 

(7) Condensers, pumps, steam gauges. 

(m) Strength of materials, including simple 
problems in proportions of marine engines and 
boilers. Inspection of materials. 

(?i) Screw propellers. Description of common 
types; definitions and simple problems connected 
therewith. 

7. The professional examination will be com- 
petitive, and all candidates who pass the mini- 
mum standard will be placed upon an eligible 
list in the order of proficiency exhibited by them 
respectively, in the examination. From this list 
selections will be made in regular order as vacan- 
cies occur, until another examination is held. 

8. The standard of proficiency has been fixed at 
75 per cent. , and candidates failing to obtain that 
average will be rejected. They may, however, if 
otherwise qualified, take another examination 
when the next board shall be convened. Failure 
in the second examination will result in the final 
rejection of the candidate. 

9. No person shall be originally appointed to a 
higher grade than that of second assistant engineer. 

10. Any person producing a false certificate of 
age, time of service, character, or making a false 
statement to the Board of Examiners, shall be 
disqualified for appointment. 

11. An} r person who subsequent to his exami- 
nation may become disqualified from moral consid- * 
erations, will not be recommended for appointment. 

12. All correspondence with reference to the 
provisions of this order should be addressed to 
the Secretary of the Treasury, AYashington, D. C. 



L 



STEAM ENGINEERS AND ELECTRICIANS. 227 



ELECTRICAL QUESTIONS. 

QUESTIONS FOR DYNAMO TENDERS. 

(Based upon low-pressure, direct-current work.) 
i 

Q. What are the essential parts of a dynamo ? 

A. The armature, the field magnet, and com- 
mutator and brushes. 

Q. What are the functions of these parts ? 

A. The magnet and armature when moved rela- 
tively to each other set up an electric pressure 
between the ends of the armature coils. When- 
ever the two ends are connected by a conductor 
an electric current will flow ; the commutator 
and brushes serve to collect the current and to 
make the current flow always in the same direc- 
tion in the external circuit. 

Q. What do you mean by the external circuit ? 

A. That portion of the circuit outside of the 
dynamo. 

Q. What analogy has a dynamo to a pump ? 

A. The dynamo may be considered as a pump 
which raises electricity from a low level or pres- 
sure to a high level or pressure. 

Q. Upon what does the pressure produced by the 
dynamo depend? 

A. Upon the number of turns of wire in the 



228 QUESTIONS AND ANSWERS FOR 

armature coils, upon the strength of the field 
magnets and upon the speed of revolution. 

Q. What would be the effect on a given dyna- 
mo of increasing the speed of the driving engine ? 

A. It would increase the pressure furnished by 
the dynamo, although not in an exact proportion 
to the change in speed. 

Q. How is an armature constructed practically ? 

A. The armature consists first of a shaft on 
which are mounted a large number of thin, cir- 
cular, iron discs. These discs are held together 
by bolts and are fastened to the armature shaft by 
a sort of spider. These discs together form a cyl- 
inder the outer surface of which has usually a 
number of grooves cut in it running parallel to 
the armature shaft. The coils of the armature, 
which consist of copper wire insulated with cot- 
ton, are wound around the cylindrical core, the 
wires being laid in the grooves. The grooves are 
generally lined with a thin insulating material 
such as paper fiber or even mica, and the wires 
are painted over with shellac or special armature 
varnish. Finally, on the outside are wound bind- 
ing wires so as to hold the armature coils in place. 

Q. What is the purpose of the cylindrical iron 
core in the armature ? 

A. If the iron core were not used a large part 
of the magnetism produced by the field magnet 



STEAM ENGINEERS AND ELECTRICIANS. 229 

would be wasted, as the magnetic lines of force 
would not pass across the space wherein the arma- 
ture coils rotate. The iron core keeps these lines 
of force within the proper space. 

Q. What is the object of making the core of 
thin discs rather than of solid metal ? 

A. If it were made of solid metal it would 
become very hot, and this would not only produce 
a waste of energy, but it would also injure and 
perhaps entirely destroy the insulation of the 
armature coils. 

Q. Is the magnet of the dynamo a permanent 
magnet ? 

A. In early dynamos it was ; in modern times 
it is always an electro-magnet. 

Q. What is an electro-magnet ? 

A. An electro-magnet consists of a piece of iron 
or soft steel surrounded by a coil of wire carrying 
an electric current. 

Q. How many poles has an electro-magnet ? 

A. It must have at least two, or it may have 
any even number of poles, such as 2, 4, 6, 8, etc. 
In any case half are of one polarity and the other 
half of the opposite polarity. 

Q. How are dynamo machines classified accord- 
ing to the winding of their field magnets ? 

A. Into three classes: Series, shunt, and com- 
pound machines. 



230 QUESTIONS AND ANSWERS FOR 

Q. What is a series machine ? 

A. A series machine is a dynamo through 
whose field-magnet coils flows all the current pro- 
duced by the machine. This is accomplished by 
taking a wire from one brush, carrying it the re- 
quired number of times around the field magnet 
and then connecting it to the external circuit ; the 
other end of the external circuit is connected to 
the other brush. 

Q. What is a shunt dynamo ? 

A. One in which only a portion of the total 
current of the machine passes through the field- 
magnet coils. 

Q. What is a compound dynamo ? 

A. A dynamo having two windings: one series 
winding, around which the main current flows ; 
and a shunt winding, through which a fraction of 
the main current flows. 

Q. For what class of work is a shunt machine 
used? 

A. A shunt machine is used when it is desired 
to maintain a constant pressure at all loads. 

Q. Does a shunt machine maintain a constant 
pressure at all loads ? 

A. Nearly so; the pressure falls off a little as 
the load increases. 

Q. What system of distribution requires a con- 
stant pressure at all loads ? 



STEAM ENGINEERS AND ELECTRICIANS. 231 

A. The ordinary parallel or multiple system 
used for the lighting' of buildings. 

Q. Are shunt machines used in general for this 
class of work ? 

A. Xo; they have been superseded very largely 
by the compound machine, which gives a closer 
regulation of pressure. 

Q. What is meant by an overcompounded 
machine ? 

A. One which automatically raises the pressure 
a little in proportion as the load increases. 

Q. What are the advantages of such a machine 
over one that would maintain the pressure abso- 
lutely constant? 

A. Such a machine would make up for a slight 
fall in the speed of an engine, which takes place 
as the load increases; it also makes up for a loss 
in pressure on the circuit wires, which loss is pro- 
portional to the load which they carry. 

Q. How is overcompounding actually obtained ? 

A. By increasing the number of turns in the 
series coil of a compound machine above what 
would be necessary to give a constant pressure 
machine. 

Q. Can the pressure furnished by a shunt or 
compound dynamo be varied ? and if so, how ? 

A. Yes; it could, of course, be varied by alter- 
ing the speed of the engine, but the common 



232 . QUESTIONS AND ANSWERS FOR 

method is to insert an adjustable resistance called 
a " rheostat" in series with 'the shunt field coils. 
When the arm of the rheostat is turned one way 
more resistance is thrown into the shunt circuit, 
which cuts down the current flowing around the 
coils. As this diminishes the strength of the 
field magnet the pressure furnished by the 
machine is lessened. Moving the rheostat arm 
in the other direction cuts out resistance and 
raises the pressure. 

Q. How are machines classified with regard to 
their field magnets ? 

A. They are classified according to the number 
of poles into bi-polar, or two-pole machines, and 
multi-polar, when the number of poles is greater 
than two. 

Q. How does the number of brushes compare 
with the number of poles ? 

A. As a rule, there are as many sets of brushes 
as there are poles. 

Q. What are the two principal methods of 
winding armatures? 

A. The ring winding and the drum winding. 

Q. Explain what must be done in setting the 
brushes so as to secure freedom from sparking. 

A. In a bi-polar machine the positive and neg- 
ative brushes must be exactly opposite each 
other. In the four-pole machine these brushes 



STEAM ENGINEERS AND ELECTRICIANS. 233 

must .be at a distance of 90 degrees from each 
other. In any case the brushes must fit the sur- 
face of the commutator accurately, and the rocker 
arm which carries them must be turned into the 
position of least sparking. 

Q. What care must be given to a dynamo in 
order to make it run properly ? 

A. It must be kept clean and dry. The bear- 
ings, of course, need no more nor no less atten- 
tion than similar bearings in other machinery. 
The parts which require the most care are the 
commutator and brushes. 

Q. Explain in detail what care must be given 
to the commutator. 

A. The commutator should be kept clean by 
occasionally wiping it with a hard-cotton cloth, 
and a very little vaseline should occasionally be 
put on it so as to diminish the friction between 
the commutator and brushes. Oil should never 
be put on it. The commutator will in course of 
time become roughened, and therefore it should 
be occasionally smoothed by holding a piece 
of very fine sandpaper against it while the 
machine is turning. If the commutator gets out 
of true it must be turned down. 

Q. How is the commutator turned down in the 
case of a small-sized armature? 

A. The armature is taken out from its bearings 



234 QUESTIONS AND ANSWERS FOR 

and mounted in a lathe, and the commutator is 
turned off just like any other piece of metal. 

Q. Is there any particular necessity for observ- 
ing care in turning down the commutator ? 

A. Yes ; the tool should take only a very fine 
cut, and after the job is finished the commutator 
should be very carefully examined to see that no 
two commutator segments have been accidentally 
connected by a little piece of copper that has 
been partially torn off from one segment by the 
cutting tool and pushed over so as to touch the 
next segment. 

Q. Suppose that there had been a connection 
established between two commutator segments and 
that this had not been discovered ; the armature 
is then. put back in place and the machine started 
up, what would be the effect ? 

A. The coil whose ends are connected to these 
two commutators would become very much heated, 
and unless the machine were stopped the whole 
armature would become badly damaged. There 
would also probably be considerable sparking at 
the brushes. 

Q. After the brushes are once properly fitted so 
that the machine runs without sparking, what care 
must be given to them ? 

A. They must be occasionally cleaned, and if 
any sparking occurs they should be immediately 



STEAM ENGINEERS AND ELECTRICIANS. 235 

adjusted so as to stop it. If the brushes are of 
copper they should be raised from the commutator 
whenever the machine is stopped, so that they 
may not be injured in case the machine were for 
any reason turned backward. 

Q. "What would be the effect of allowing the 
dynamo to become wet ? 

A. The insulation of the armature and field 
coils would be injured if not entirely destroyed. 
It would be, as we say, grounded — that is, put in 
electrical connection with the frame of the machine. 

Q. What do you mean by the term ' ' badly 
grounded ' ' ? 

A. The armature, for example, would be badly 
grounded if the insulation resistance between the 
coils and the iron core became very low. 

Q. How many ohms insulation resistance be- 
tween the armature or field coils and the frame is 
it usual to demand in a good dynamo ? 

A. An insulation resistance of at least 1,000,000 
ohms. 

Q. How could you determine whether or not 
the machine were grounded ? 

A. I should take a magneto bell and connect 
one terminal to the frame of the machine, being 
careful to have the connection on a metal surface 
which had been made clean and bright. The 
other terminal of the magneto I would connect to 



236 QUESTIONS AND ANSWERS FOR 

one of the brushes. It is understood that the 
machine is not to be operated while the test is 
being made. I would then turn the handle of 
the magneto, and if the bell sounded I should 
know that there was a bad ground somewhere in 
the machine. To locate it I would raise the 
brushes from the commutator and turn the mag- 
neto again. If it rings this shows that there is a 
ground either in the brush holders or in the field 
circuit. I would then disconnect the field circuit 
from the brush holders and test each separately, 
and after having found, for instance, that the 
ground was in the field coils I would disconnect 
them so as to find in which particular coil the 
trouble existed. I would afterward test the 
armature to find if there were any ground 
in it. 

Q. In case you found that there was a ground 
in the armature, what would you do ? 

A. I would examine it carefully, especially at 
the commutator end, to see if it were caused by a 
collection of metal dust and oil or by anything 
else which I could remedy. If the cause of the 
trouble could not be found it would be necessary 
to take the armature out and send it to some shop 
where they make a specialty of rewinding arma- 
tures. 

Q. Suppose that you were at a distance from 



STEAM ENGINEERS AND ELECTRICIANS. 237 

such a shop, would you attempt to repair the 
trouble yourself ? 

A. If it were a small ring- wound armature I 
might do so, but certainly would not attempt it 
in any other case. 

Q. Suppose that a ground were found to exist 
in one of the field coils, what would you do? 

A. I should not hesitate to attempt to repair 
that. I would take out the spool on which the 
coil is mounted and would put it in a lathe and 
carefully unwind the coil, winding the wire up at 
the same time on some sort of drum or reel so as 
not to kink or injure it in any way. I would 
occasionally test with a magneto bell, connecting 
one terminal to the metal of the spool and the 
other terminal to the wire, and would keep on 
unwinding until the coil showed free from a 
ground; then I would repair the place where the 
trouble was found by putting in some new insula- 
tion or new wire as might be needed, and would 
carefully wind back the wire in exactly the same 
way that it had been wound by the manufacturer. 
I would then replace the spool in the machine, 
testing again for grounds, and would reconnect the 
machine, and after making a final test for grounds 
would start it up. 

Q. What is a direct connected machine ? 

A. A direct connected dynamo is one which is 



238 QUESTIONS AND ANSWERS FOR 

driven by an engine without the use of the belt ; 
either the armature shaft is connected to the en- 
gine shaft by means of the flexible coupling or 
more commonly the engine shaft is made extra 
long with an out-board bearing, and the armature 
is mounted on this shaft, the field magnets being 
attached to the extended bedplate of the engine. 

Q. What advantages and disadvantages can you 
think of in connection with direct connected 
dynamos ? 

A. Their advantages are : economy of space, 
quietness in operation, and increased efficiency, 
since losses in belt transmissions are done away 
with. Such generators are, however, more costly, 
since they must run at a comparatively low speed, 
they being subject in this respect to the limita- 
tions of the engine. A belted machine may have its 
frame thoroughly insulated from earth while the 
direct connected machine, if the armature is 
mounted on the engine shaft, cannot enjoy this 
advantage. 

Q. Does a single ground on the circuit or in the 
machine do any harm ? 

A. No ; it requires two grounds. Nevertheless, 
in case a ground exists it should be promptly 
located and the trouble remedied. 

Q. In case of two grounds existing, what things 
may occur? 



STEAM ENGINEERS AND ELECTRICIANS. 239 

A. The fuse or fuses may blow ; one or more of 
the conductors may become overheated or a spark 
may pass across the grounded spot, and either of 
these last two effects may set fire to any combus- 
tible matter in the vicinity. 

Q. Explain the general method by which elec- 
trical energy is distributed for ordinary house 
lighting. 

A. The distribution is very similar to a water 
system in which water is pumped from a tank at 
a low level to an elevated tank and then led from 
this tank through pipes to the various points 
where it is. to be used, and after having been used 
is led back through another set of pipes to the low 
level tank from which the water is again pumped 
up to be used again. The dynamo corresponds to 
the pump ; the copper wires correspond to the dis- 
tribution pipes and the two bus bars on the 
switchboard correspond to the two tanks. The 
switches correspond to the valves, the ammeters 
correspond to water meters, and the voltmeters 
correspond to pressure gauges. 

Q. What is the high-pressure system of con- 
ductors called in electrical distribution ? 

A. The positive, or plus (+). 

Q. What is the low-pressure set of conductors 
called? 

A. The negative, or minus ( — ). 



240 QUESTIONS AND ANSWERS FOR 

Q. Explain how, practically, a generator is con- 
nected to a switchboard, describing the materials 
used and the manner in which they are in- 
stalled. 

A. There are several methods of construction.. 
The conductors may be carried overhead ascend- 
ing vertically from the machine terminals to the 
ceiling of the dynamo room and then across the 
ceiling and vertically downward to the fuse termi- 
nals of the machine switches on the switchboard. 
In this class of construction the conductors may be 
bare copper rods or may be wire insulated with 
fire- and weather-proof or rubber insulation. The 
conductors in either case are attached to porcelain 
insulators. If bare copper rods be used, that por- 
tion of their length which is near the generator 
should be covered with insulating tape. 

Another and more common method is to carry 
the conductors under the floor of the dynamo 
room, placing them in iron pipe or conduit ; in this 
case the conductors should be insulated with rub- 
ber, or a lead-covered cable may be used. 

A third method is to carry the conductors under 
the floor in a brick or concrete duct covered with 
iron plate ; in such cases the conductors may be 
mounted on porcelain, but as this necessitates a 
very large duct it is better to use for conductors a 
lead-covered cable. 



STEAM ENGINEERS AND ELECTRICIANS. 241 

Q. Trace the connections from the generator ta 
the bus bars, stating through what pieces of appa- 
ratus the current would pass. 

A. Starting from the positive brush the con- 
ductor runs from the brush to a fuse terminal on 
the machine switch ; the current after passing 
through this fuse passes through the positive blade 
ot the machine switch and then through the 
ammeter (or ammeter shunt) and through a con- 
necting strip to the positive bus bar. From the 
negative bus bar the current passes through a cop- 
per strip to the machine switch, through the blade 
of the switch and the corresponding fuse and 
then through a conductor which extends from the 
fuse terminal to the negative brush. 
_ Q. What is the object of a fuse, and of what is 
it made ? 

A. A fuse generally consists of a piece of com- 
position metal,— usually some alloy of lead which 
will melt at a fairly low temperature,— soldered 
to copper terminals, these terminals being of such 
shape that they may be conveniently clamped 
under lugs provided to receive them. The fuse is 
intended to melt whenever a current exceeding a 
certain strength passes through it. It therefore 
serves to protect either the circuit conductors 
or the machine from overheating due to the pas- 
sage of too great a current. 
16 



242 QUESTIONS AND ANSWERS FOR 

Q. What are used instead of fuses, and what 
are their advantages ? 

A. Circuit breakers. They are more certain in 
their action, especially with large currents. The 
large fuses which must be used for large currents 
are very unreliable, and fuses, for example , which 
are intended to melt with a current of, say, 500 
amperes may be melted by a current below that 
value or may not blow until the current has risen 
to perhaps 1000 amperes. 

Q. What is the general principle on which cir- 
cuit breakers are constructed ? 

A. A circuit breaker is essentially a switch 
which automatically opens when the current ex- 
ceeds a certain amount. It is closed against the 
pressure of the spring, which pressure will throw 
it open if the switch is not held in by a sort of 
trigger or catch. This trigger is controlled by a 
coil through which the current passes. If the cur- 
rent becomes greater than a certain value the coil 
sucks up an iron rod attached to the trigger and 
releases it; the compressed spring then being free 
to act upon the switch interrupts the circuit. 

Q. What circuit breakers are usually provided 
by the switchboard ? 

A. One for each generator. In many installations 
each feeder circuit is provided with a circuit 
breaker, no fuses at all being: used on the board. 



STEAM ENGINEERS AND ELECTRICIANS. 243 

Q. What is the difference between a double-pole 
breaker and single-pole circuit breaker ? 

A. The same difference as exists between a 
double-pole switch and a single-pole switch. The 
double-pole switch when open interrupts both the 
positive and negative sides of the circuit ; the 
single-pole interrupts only one side. 

Q. Which kind of circuit breaker is the better 
to use, a double or single pole ? 

A. The double pole. 

Q. When single-pole circuit breakers are used 
with compound machines, in which of the con- 
nections between the djmamo and switchboard 
must the circuit breaker be placed ? 

A. In the side opposite that in which the series 
coil is connected. 

Q. When two or more compound machines are 
run together, how many connections run from the 
dynamo to the switchboard from each machine ? 

A. There are three large conductors — namely, 
the positive, the negative, and the equalizer. 

Q. What is the purpose of the equalizer connec- 
tion, and what does it connect ? 

A. The equalizing connection runs from the 
inner end of the series field coil to the correspond- 
ing point on the other machine. It passes from 
machine No. 1 to a switch on the switchboard, 
then back to machine No. 2. If there are more 



L 



244 QUESTIONS AND ANSWERS FOR 

than two machines the equalizing connection runs 
from the series coil to the switch on the board and 
from the switch to an equalizer bus bar. The 
purpose of the equalizing connection is to enable 
the machines to be operated together satisfactorily. 
If it were not used the machines would not tend 
to divide up the total load properly. By adjust- 
ing the rheostats the machines can be made to take 
their proper share of the load without the equal- 
izing connection; but if the speed of one engine 
diminished slightly the machine corresponding 
would take a much less portion of the load, and 
this action would be aggravated so that shortly 
one machine would be carrying all the load and 
perhaps driving the other as a motor. The equal- 
izing connection prevents this action. 

Q. What small connections are there between 
the generators and the switchboard ? 

A. The field connections which may be run in 
either of two ways. First, the outer end of the 
field coil on the generator is connected to one 
of the rheostats by a wire and a return wire con- 
nects the other terminal of the rheostat to a brush 
of the proper polarity; in the second method the 
return wire is omitted, a connection being made 
between the rheostat terminal and the bus bar of 
the proper polarity. 

Q. What are the principal devices to be found 



STEAM ENGINEERS AND ELECTRICIANS. 245 

on a switchboard, and what is the purpose of 
each? 

A. (1) An ammeter in the circuit of each gener- 
ator for the purpose of measuring the current 
passing through each machine. (2) One or more 
voltmeters. If only one voltmeter be used it is 
provided with a many point switch by which it 
may at will be connected to the bus bar or to the 
terminals of any generator. If there be two volt- 
meters, one is connected permanently to the bus 
bars and the other is provided with a switch. (3) 
A rheostat for each generator, by which the pres- 
sure furnished by each machine may be varied. 
(4) Circuit breakers or fuses in the machine cir- 
cuits and in the feeder circuits, whose function is 
to interrupt any particular circuit through which 
an excessive current may for any reason flow. (5) 
Switches for disconnecting the generators from the 
bus bars. (6) Switches for disconnecting the dis- 
tribution circuits from the bus bars. (7) A ground 
detector whose purpose is to -show if any part of 
the circuit becomes connected to the earth. 

Q. Explain the arrangement and action of a 
two-light ground detector when used on a 110- 
volt circuit. 

A. The two-light ground detector consists of 
two 110- volt lamps connected in series across the 
bus bars. A point on the circuit between the two 



246 QUESTIONS AND ANSWERS FOR 

lamps is connected to earth by attaching it to a 
convenient water pipe. The operation is as fol- 
lows: So long as the insulation of the system is 
unimpaired the two lights will burn dimly and 
equally so, since they have only 55 volts pressure 
between their terminals. If, however, there is a 
bad ground on one side of the circuit, say, the 
positive, the lamp connected to the positive side 
will become very much more dim, since there is 
now an auxiliar}^ circuit across its terminals 
through the earth. The other lamp will burn 
brightly, since the pressure between its terminals 
is very much greater than before. 

Q. Suppose that one of the ground detector 
lamps burns brightly, how would you proceed, 
practically, to find the ground ? 

A. I would open the circuit switches one by one 
and watch the ground detector to see if the open- 
ing of any one of them made the lamps again 
both burn equally dim. If this were the case I 
should know that the ground were located on that 
part of the circuit controlled by this switch. I 
would then go out to the first distribution board 
on that circuit with a portable ground detector, if 
I had one, and connect it up at that point. I 
would then open the switches or fuses one by one 
until I found which branch contained the ground. 
I would then leave that branch disconnected and 



STEAM ENGINEERS AND ELECTRICIANS. 247 

with a magneto bell would test different parts of 
that branch circuit, splitting it up into sections at 
some convenient outlet or switch. In this man- 
ner the ground would be located within quite 
close limits. If I found that the ground were on 
a short piece of the circuit on which a fixture were 
connected I would disconnect the fixture, and 
test with the bell both the fixture and the wiring. 
If the wiring showed the ground I would run in a 
new piece of wire to take its place. 

Q. When three-pole switches are used for 
machine switches, what is connected to each 
blade? 

A. The positive side of the generator to one of 
the outside blades, the equalizer to the middle 
blade, and the negative side of the machine to the 
other outside blade. 

Q. May shunt machines be run together in 
multiple? 

A. Yes. 

Q. Do shunt machines when run in multiple 
need an equalizer? 

A. No, 

Q. Explain how you would proceed if you had 
one machine in operation and you desired to start 
up a second in multiple with it to take care of an 
increase in load, both machines being compound. 

A. I would start up engine No. 2 and adjust 



248 QUESTIONS AND ANSWERS FOR 

its rheostat until the voltmeter showed its pres- 
sure to be about \ volt greater than that of 
machine No. 1. If each machine had a three-pole 
switch I would close the switch of No. 2, adjust- 
ing the rheostat handles until the ammeters read 
alike (if the machines are of the same size) and 
the bus bars are at the desired voltage. If the 
machines have a two-pole switch with a separate 
switch for the equalizer, I would close the equal- 
izer switch first and then close the double-pole 
machine switch, afterward adjusting the rheostats. 

Q. Sometimes you will see a switch in the field 
circuit. Should this ever be opened when that 
machine is in operation ? 

A. Never. 

Q. What would be the effect of opening the 
switch ? 

A. It would produce a strong spark at the 
switch, and would be liable to seriously injure the 
insulation of the field coils of the machine, be- 
cause the opening of the circuit produces for a 
moment a very high electric pressure that is liable 
to pierce the insulation. 

Q. Suppose two machines designed for 400 
amperes each are operating in multiple on a load 
of 600 amperes, and the fuses or circuit breaker 
of one of the machines opens the circuit, what 
effect would you notice ? 



STEAM ENGINEERS AND ELECTRICIANS. 249 

A. There would probably be great sparking or 
flashing at the commutator of the other machine, 
because it would be very much overloaded. 

Q. What would you do in this case ? 

A. Quickly open the circuit switches one by 
one ; and if this did not remedy the trouble, open 
the machine switch; and if this did not stop it, 
turn the rheostat handle so as to lower the voltage 
to the smallest possible amount and shut down 
the engine. If the trouble were due to nothing- 
more than overloading, it would be remedied by the 
opening of a sufficient number of circuit switches. 

Q. What are some of the troubles to which 
rheostats are liable ? 

A. Some of the coils may be burned out or 
grounded, or some of the contacts may become 
defective. 

Q. In case a single machine is running and a 
coil of its rheostat should burn out, what would 
be the effect ? 

A. The lamps on the circuit would all go out, 
since the opening of the field circuit would de- 
stroy the magnetism of the machine and it would 
furnish no pressure. 

Q. How would you remedy the difficulty tem- 
porarily ? 

A. By connecting wire across the terminals of 
the burned- out coil. 



250 QUESTIONS AND ANSWERS FOR 

Q. Suppose that two machines were running in 
multiple at the time the rheostat coil burned out, 
what would happen ? 

A. One of the machines would become over- 
loaded, producing serious sparking or flashing. 

Q. Suppose that one coil of the rheostat be- 
came grounded, how would you remedy it ? 

A. By disconnecting that coil from the others 
and putting in a temporary connection of wire to 
take its place. 

Q. What are some of the methods of construct- 
ing rheostats for dynamos ? 

A. The older method was to make up coils of 
wire insulated on porcelain or other suitable 
material and mounted in an iron framework or 
box, the terminals of the coils being connected to 
suitable brass plates over which the rheostat arm 
played. The more modern method is to imbed 
the wire coils in an insulating enamel, the wires 
being wound in a flat coil instead of a spiral, so 
that they may lie very close to the iron frame- 
work ; this construction gives much greater com- 
pactness. 

Q. How is the Weston switchboard voltmeter 
constructed ? 

A. It consists of a permanent magnet of horse- 
shoe form between the poles on which is pivoted 
a small coil of very fine wire connected to proper 



STEAM ENGINEERS AND ELECTRICIANS. 251 

terminals. Whenever a current passes through a 
wire the coil tends to turn in a certain direction 
against the action of springs which tend to hold it 
in place. The stronger the current the greater the 
deflection of the coil. Attached to the coil is a 
light needle which plays over a graduated scale. 

Q. How does the ammeter differ from this ? 

A. The ammeter is constructed in the same 
way, but only a very small fraction of the current 
to be measured passes through the coil. The 
greater part of the current passes through the 
shunt of the instrument, this shunt being placed 
in one of the leads coming from the machine. 
The terminals on the shunt are connected to the 
terminals on the ammeter through a pair of flexi- 
ble leads about ten feet long. 

Q. Would it do any harm to cut off a part of 
these leads ? 

A. Yes ; it would totally destroy the accuracy 
of the instrument. Each instrument requires a 
special pair of leads of the proper resistance. 

Q. How could you roughly test the accuracy of 
your ammeters ? 

A. By operating first one machine on a certain 
number of lamps at 110 volts exactly ; then throw 
off that machine and operate the same number of 
lamps with the other machine at the same pres- 
sure. If the readings of the ammeter ^vere prac- 



252 QUESTIONS AND ANSWERS FOR 

tically the same in the two cases it is fair to 
assume that they are reasonably correct. The 
ammeters can also be tested against the circuit 
breakers. If the circuit breaker always goes off at 
the same reading of the ammeter it may be as- 
sumed that the ammeter has not lost its accuracy. 

Q. How can the voltmeter be tested by com- 
parison with some other voltmeter supposed to be 
correct ? 

A. The two voltmeters are connected up in 
multiple across the bus bars. 

Q. Would you attempt to repair an ammeter or 
voltmeter that was out of order ? 

A. On no account. 

Q. How does a direct current motor differ from 
a dynamo as regards construction ? 

A. Only in details of design. Practically, any 
direct current dynamo will operate satisfactorily 
as a motor if current be supplied to it. 

Q. What would you do in case you desired to 
reverse the direction in which a motor runs ? 

A. I would change the connections so as to re- 
verse the direction of current through either the 
field or the armature, and if necessary to prevent 
sparking would shift the rocker arm that carries 
the brushes. 

Q. For what class of work are series motors 
used? 



STEAM ENGINEERS AND ELECTRICIANS. 253 

A. Series motors are used in those cases where 
it is necessary to start with full load and where 
automatic regulation for constant speed is not 
necessary, as in hoists, cranes, street railway, 
etc. J ' 

Q^ When are shunt motors used ? 
A. 9 In those cases where automatic regulation 
tor constant speed is desired. 

Q. Are compound motors ever used ? 
A. Yes ; in cases where closer speed regulation 
than that given by shunt motors is desired. 

Q. How is the change of speed accomplished in 
the case of the series motor supplied from a con- 
stant pressure circuit ? 

A. There are two methods commonly used 
One is to change the pressure supplied to the 
motor by putting in series with it a rheostat in 
which more or less pressure is used up according 
to the position of the rheostat handle. Lowering 
the pressure supplied to the motor lowers its 
speed, and vice versa; the other is to change the 
strength of the field of the motor. The field 
coils are wound in sections, and the ends of the 
sections are brought out to a species of commu- 
tator called the controller. In one position of the 
controller handle the sections are connected in 
series, which cuts down the current strength and 
makes the field magnet comparatively weak In 



254 QUESTIONS AND ANSWERS FOR 

the next position three of the sections, for ex- 
ample, will be in series, and three others in series, 
and the two sets of three will be connected in 
multiple. This arrangement diminishes the re- 
sistance of the circuit and lets more current 
through; another position puts more sections in 
multiple and fewer in series, and so on until the 
final step puts all the sections in multiple, giving 
the lowest possible resistance and the strongest 
possible field. Frequently, the combination of 
the two methods is used, the resistance being em- 
ployed on the first positions of the rheostat 
handle in order to cut down the excessive flow of 
current on starting. 

Q. In what way are shunt motors regulated for 
changes in speed when supplied from constant 
pressure circuits ? 

A. By putting resistance coils in series with the 
armature and cutting out more or less of them 
according as a higher or lower speed is desired, or 
b}' putting a rheostat in series with the field cir- 
cuit and varying the current around the field coils 
by adjusting the rheostat handle. 

Q. How are compound motors regulated for 
changes in speed ? 

A. Generally like shunt motors, although in 
some cases the series coils are wound in sections 
thrown in series and multiple by the controller. 



STEAM ENGINEERS AND ELECTRICIANS. 255 

Q, In starting up a shunt or compound motor, 
what precaution is necessary and why ? 

A. Considerable resistance must be put in series 
with the armature. If this were not done the 
very low resistance of the armature would permit 
the flow of an enormous current which would 
blow fuses or overheat the armature coils and 
cause excessive sparking at the brushes. As the 
machine speeds up this resistance is cut out. 
The whole arrangement is automatically arranged 
for by the starting box that is supplied with each 
motor. 

Q. What other protective devices are required 
with shunt motors ? 

A. Motors must be protected from the danger 
of overload which by slowing down the motor 
diminishes its back electro-motive force. This 
would allow an excessive current to flow, which if 
long continued would burn out the armature 
coils. Formerly this protection was provided by 
fuses. At the present time a circuit breaker 
mounted on the starting box is almost universally 
employed. Another thing that must be guarded 
against is the accidental temporary interruption of 
the supply circuit (which would of course stop 
the motor) and its being subsequently closed 
again. If this happened it would throw full 
voltage on the motor armature, and this would 



256 QUESTIONS AND ANSWERS FOR 

result in an excessive flow of current. To guard 
against this difficulty the starting box is arranged 
so that whenever the pressure of the circuit is 
diminished below a certain amount or is zero in 
case of actual interruption of the circuit, the rheo- 
stat arm is pulled back into the position which 
throws a resistance in series with the armature. 

Q. What is a motor generator ? 

A. A combination of motor and generator on 
the same shaft. 

Q. How are dynamos and motors rated ? 

A. Dynamos are rated, as regards their capacity, 
in kilo watts, and motors are rated in horse-power. 

Q. What is the relation between the kilo watt 
and the horse-power ? 

A. One horse-power is practically equivalent to 
§ kilo watt. 

Q. What is the arrangement of the Edison 
three-wire system ? 

A. See " Roper's Catechism," page 311. 

Q. Can a system of house wiring installed on 
the Edison three-wire system be operated from 
one machine, and if so, how ? 

A. Yes; the two outside feeders must be con- 
nected together so as to be of the same polarity 
and joined to one of the brushes or bus bars. 
The neutral feeder must be connected to the other 
brush or bus bar. 



STEAM ENGINEERS AND ELECTRICIANS. 257 

Q. Is this arrangement ever employed in prac- 
tice ? 

A. Often; it is arranged so that the change of 
connections is made by a double-throw switch. In 
one position of the switch the house circuit is 
thrown on to the Edison mains; in the other posi- 
tion of the switch the circuit is thrown on to the 
house generator. 

Q. What is the commercial efficiency of a 
dynamo ? 

A. It is the ratio between the amount of elec- 
tric power furnished by the dynamo and the 
amount of mechanical power delivered to the 
dynamo. 

Q. How can the efficiency of a dynamo be 
measured ? 

A. By indicating the engine when the dynamo 
is full loaded and noting the reading of the am- 
meter and voltmeter, then indicating the engine 
when the dynamo is running idle with no current 
flowing through the fields. The difference between 
the horse-power of the two indicator diagrams is 
very closely the amount of mechanical power sup- 
plied to the dynamo. The product of the volts 
and amperes divided by 746 gives the power de- 
veloped by the dynamo ; the quotient of the lat- 
ter by the former is the commercial efficiency of 
the dynamo. 
17 



258 QUESTIONS AND ANSWERS FOR 

QUESTIONS FOR ELECTRICIANS OR WIREMEN. 

Q. What are the principal systems of distribu- 
tion for electric lighting? 

A. The series system and the parallel system. 

Q. What is the difference between the two s}*s- 
tems ? 

A. In the series system the lamps are connected 
in tandem, the entire current flowing successively 
through each lamp. In the multiple system the 
current from the dynamo is divided, a part flow- 
ing through each lamp. After passing through 
the lamps the separate currents unite and flow 
back to the dynamo. 

Q. On which of these systems are motors gener- 
ally operated ? 

A. On the parallel system. 

Q. To what class of work is the series system 
practically confined? 

A. To outside arc lighting. 

Q. What is the vital necessity on a series sys- 
tem to make the lighting successful ? 

A. The series system must be a constant cur- 
rent system ; that is to say, cutting out or in more 
or less of the lamps must not alter the value of 
the current. 

Q. What is necessary on the multiple or paral- 
lel system ? 



STEAM ENGINEERS AND ELECTRICIANS. 259 

A. This system is necessarily a constant poten- 
tial or constant pressure system — that is, turning 
on or of! lamps must not materially alter the pres- 
sure on any other lamps. 

Q. "What is the Edison three- wire system ? 

A. The Edison three- wire system is a peculiar 
combination of series and multiple systems. Two 
lamps are placed in series with each other and the 
sets of two are in multiple with each other. A 
conductor, called the neutral, connects the point 
of junction of the lamps which are placed in 
series with each other and runs to the point of 
junction of the two generators (in series with each 
other) which supply the system. 

Q. What is the advantage of the Edison system ? 

A. The Edison system secures economy in the 
size of wire, from the fact that it permits the dis- 
tribution at a higher pressure without saiy serious 
disadvantages ; for example, the distribution on 
the feeders and mains is essentially at 220 volts", 
while the pressure on the branch circuits and the 
lamps is only 110 volts. 

Q. Could not the same economy be obtained by 
using a simple multiple system with 220-volt 
lamps ? 

A. Yes; but it is difficult to make good 220- 
volt lamps and 110- volt lamps are superior to 
them. Moreover, the lower pressure lamp is more 



260 QUESTIONS AND ANSWERS FOR 

desirable from the standpoint of safety, since 
there will be less liability to leakage from the cir- 
cuit when the lower pressure is used. A shock 
from the 110 volts is scarcety noticeable or at any 
rate not disagreeable, while the shock from 220 
volts is quite severe. 

Q. What determines the necessary size of wire 
in any particular case ? 

A. There are two requirements which must be 
met -.'First, the wire must be large enough so that 
the current that will flow through it will not heat 
it beyond a certain amount; this requirement has 
been definitely laid down by the Fire Under- 
writers, who provide tables stating the allowable 
current for various sizes of wire. Second, the 
size of wire is determined by the aimount of 
energy which we are willing to lose on it. This 
loss of energy depends on the current that will 
flow and the resistance of the conductor. 

* Q. What loss of pressure is allowable on con- 
ductors ? 

A. There is no definite rule for this. In build- 
ings, the total loss of pressure from the gener- 
ator to the most distant lamps seldom ex- 
ceeds 5 per cent, and with the ordinary system 
of multiple wiring is rarely more than 3 per cent, 
of the voltage of the lamps. A part of the loss is 
on the feeders, another part on the mains, and the 



STEAM ENGINEERS AND ELECTRICIANS. 261 

rest on the branches and in the switches, fuses, 
etc. 

Q. Explain how you would calculate the size 
of wire to be used in the following case : Ten 16 
c. p. lamps whose voltage is 110 are to be sup- 
plied by current from a dynamo 200 feet away. 
The loss permissible is 1 per cent. 

A. Since the allowable loss is 1 per cent, the 
volts lost will be 1.1. The current for ten lamps 
will be practically 5 amperes. The total length 
of wire will be 2 X 200, or 400 feet. By Ohm's 

law C = — or R-=. _ . Therefore R = -^-, or 

. 22, hence the wire must be of such size that 400 
feet, of it has a resistance of not over . 22 ohm. 1000 
feet of this size would have a resistance equal to 
.22 X 1000 divided by 400, or .275. Looking in 
the wire tables under the column headed ohms per 
1000 feet, it will be found that a No. 4 wire fulfils 
the requirement. Finally, looking in the table of 
safe carrying capacities given by the National 
Board of Fire Underwriters it is found that a No. 
4 wire will more than carry the current with 
safety. 

Q. What varieties of electric wiring are there ? 

A. Open work, such as porcelain work and 
moulding work ; and concealed, where the wires 
are carried on porcelains or in conduits. 



262 QUESTIONS AND ANSWERS FOR 

Q. What kind of conduits are used at the pres- 
ent day ? 

A. For the great bulk of the work iron or steel 
conduits, of which there are two varieties: one in 
which the tube, which is practically a gas-pipe, is 
lined with some insulating compound; the other, 
where the tube is covered inside and out by a 
hard enamel. 

Q. What is circular loom conduit, and in what 
cases can it be used and where must it not be used ? 

A. Circular loom tube is a semi-flexible con- 
duit made of paper and covered with cotton, 
which is used in buildings of wooden construc- 
tion, particularly in cases where it is desired to 
install electric work in an old building. The cir- 
cular loom is used to cover the wires run down 
partitions, since it may be fished in without injur- 
ing the finished work in the house. It is abso- 
lutely useless in those cases where it is liable to be 
subjected to moisture or is in contact with cement; 
it must therefore be regarded as a makeshift, to 
be used only in those cases where iron conduit 
cannot on account of its stiffness be installed or 
where the work could not be done on porcelain 
without destroying costly finished surfaces. 

Q. Is there any difference as to the number of 
wires carried in a C. L. tube or in an iron 
conduit ? 



STEAM ENGINEERS AND ELECTRICIANS. 263 

A. Yes; only one wire is carried in C. L. tube; 
in iron conduit two wires are carried in the two- 
wire system and three in the three-wire system, 
except occasionally in case the feeders are so large 
that it is not possible to draw more than one wire 
in the tube. 

Q. What is the best way to cut off iron con- 
duit, and why ? 

A. By means of a hack-saw. This method gives 
a smoother cut and leaves less ragged edges, and 
does not injure the lining or the enamel as much 
as the use of ordinary pipe cutters. 

Q. After cutting off a piece of pipe, what should 
be done to the ends ? 

A. They should be smoothed with a reamer or 
file. 

Q. In making joints in conduits, how should 
the joints be treated ? 

A. The pipes should be screwed into the coup- 
lings so that they butt against each other, the 
threads being previously treated with white lead 
so as to make a water-tight joint. 

Q. What are the principal troubles to be 
avoided in doing conduit work ? 

A. Too many bends, joints that are not butted 
together properly and are not water-tight, and 
rough edges at the joints and at the outlets that 
will injure the insulation of the wires. 



264 QUESTIONS AND ANSWERS FOR 

Q. How are conduit tubes fastened into outlet 
or switchboxes ? 

A. There are several methods : One is to tap 
the outlet box with a thread and screw the conduit 
into this; another is to put a lock-nut on the pipe 
outside of the box and another lock-nut inside: a 
third is to put a coupling outside and a special in- 
sulated nut inside the box, which nut screws into 
the coupling. 

Q. What are the disadvantages of the first 
method ? 

A. It is very difficult to get the switch or out- 
let box to stand plumb; especially when, as in 
the case of gang switches, several pipes enter and 
leave the box. 

Q. What is the general arrangement at a sub- 
switchboard for bringing in the tubes and wires 
conveniently ? 

A. The switchboard proper is surrounded by an 
outer wooden or iron box the walls of which are 
about 3 inches or 4 inches distant from the inner 
wall. The latter is generally made of thin slate 
or marble. The conduit tubes are brought 
through the outer box and stop there. The wires 
continue through holes in the inner slate walls 
and are attached to the proper terminals. The 
space between the inner and outer walls is covered 
by the trim of the door. By this arrangement 



STEAM ENGINEERS AND ELECTRICIANS. 265 

the rough box can be put in before the conduit 
work is done and the switchboard proper inserted 
at a later date when the building is nearing com- 
pletion and the door and trim finally put on just 
in time to be finished by the painters. 

Q. Why are ends of conduit tubes plugged up 
as soon as they are installed ? 

A. For two reasons: one to prevent any small 
objects from getting into the tubes and stopping 
them up, the other to prevent the condensation of 
moisture in the tubes, which would injure the 
insulation of the system. 

Q. What are the commercial sizes of conduit at 
the present time ? 

A. Conduits are sized according to their nominal 
internal diameter, the sizes being -f^-", J", -fa" y 
ft", 1£", W, 1*", W, and 2|". 

Q. How many bends would you allow in a run 
of conduit? 

A. That would depend somewhat on the length 
of run; in any case I w^ould not allow more than 
four. 

Q. Explain how wires are put into a conduit 
system. 

A. A springy steel wire about y\ of an inch wide 
and y 1 ^- of an inch thick, having a length usually of 
100 feet, is pushed into a length of conduit from 
one of the outlets. A man at the outlet on the 



266 QUESTIONS AND ANSWERS FOR 

other end pulls this wire through and with it a 
pulling cord or wire. The two wires to be drawn 
are then attached to the cord or wire and are gradu- 
ally worked in by the pulling on one end assisted 
by a pushing and twisting motion on the other end. 
The friction of the wire against the walls of the 
conduit is diminished by blowing in powdered 
soapstone before the wires are drawn in. 

Q. What kinds of insulation are used on wires, 
and for what class of work are these used ? 

A. The kind of insulation used depends upon 
the pressure to be used on the system. For 
electric bell and other signal work, where only a 
few cells are used, the pressure not exceeding 10 
volts, a comparatively low insulation is sufficient. 
In such cases a wire is covered with two or more 
layers of cotton impregnated in paraffin. For out- 
side wiring the conductors are covered with two 
or three layers of braided cotton, imj^regnated 
with some bituminous insulating compound. 
These wires are called weather-proof wires. For 
inside wiring on porcelain an insulation called 
fire- and water-proof has been largely used; the 
wire is covered with a cotton braid impregnated 
with w r hite lead, and afterward another covering 
of cotton braid is put on and slicked over with the 
weather-proof insulation. The practice now is 
almost universally to use an insulation made up 



STEAM ENGINEERS AND ELECTRICIANS. 267 

of a mixture of rubber and other insulating mate- 
rials, usually of a bituminous nature. The higher 
the pressure to be used, the greater the percentage 
of rubber that should be employed. 

Q. With a run of 100 feet of ^" conduit hav- 
ing three bends, how large size of wire could you 
draw in, there being two wires to the tube ? 

A. About a No. 8, B. & S. 

Q. How can you tell whether or not the con- 
ductors in a conduit tube are all right ? 

A. Roughly by means of the magneto bell. I 
would connect one terminal of the bell to the tube, 
filing a bright spot for making the connection, 
and with the other terminal of the magneto would 
touch first one of the conductors and then the 
other ' if the insulation is very bad the bell will 
ring. If not, the bell will make no noise. After 
making this test I would connect one terminal to 
the other wire and test for short circuit. If the 
bell were silent on both of these tests I should 
pssume that the wires were in good condition. 

Q. Magneto bells are sold as 10,000 ohms, 
15,000 ohms, 25,000 ohms, etc., up to 50,000 
ohms. What do these terms mean, and which • 
one would you consider best for testing ? 

A. A 50,000 ohm bell is one which is sup- 
posed to ring through a resistance connected 
across its terminals as great as 50,000 ohms. A 



268 QUESTIONS AND ANSWERS FOR 

10,000 ohm bell is supposed to ring through a re- 
sistance of 10,000 ohms. I would, of course, 
prefer the 50,000 ohm bell for testing. 

Q. What other method of testing the insulating 
resistance is more accurate ? 

A. The test with a voltmeter. 

Q. Why are two wires carried in the iron tubes ? 

A. Because it is safer and because if alternating 
currents are used on the circuit there would be 
otherwise an excessive loss of pressure. 

Q. What is a distribution board, and by what 
other names is it called ? 

A. A distribution board is a small switchboard 
where the current from a main feeder is dis- 
tributed to supply smaller feeders or branch cir- 
cuits. It contains fuse blocks and often switches. 
Other names are sub-switchboard, panel board, 
tablet board, cut-out box, and center of distribu- 
tion. 

Q. What is a fuse, and why and where is it used ? 

A. A fuse consists of a piece of metal, usually 
some alloy of lead which will melt at a fairly low 
temperature, soldered to copper terminals. It is 
intended to melt whenever the current passing 
through it exceeds the safe carrying capacity of 
the wire which the fuse is designed to protect. 
Fuses are placed at all points of a circuit where 
there is a change made in the size of the wires. 



STEAM ENGINEERS AND ELECTRICIANS. 269 

Q. What is a closed arc lamp, and what are its 
advantages over the open arc ? 

A. The closed arc lamp is one in which the 
small inner globe surrounds the arc, preventing, 
to a great extent, air from coming into contact 
with the arc. The principal advantages of the 
closed arc lamp are that the consumption of the 
carbons is very much diminished and the light is 
steadier. 

Q. At what rate do carbons burn in the two 
types of lamp? 

A. Carbons last about seven hours in the open 
arc lamp and about one hundred hours in the 
closed arc lamp. 

Q. When a single lamp is used on a constant 
pressure circuit, what is the general arrangement 
of the mechanism ? 

A. The current which comes from the line to 
the positive lamp terminal passes through a coarse 
wire coil and then through a chain or brush con- 
tact to the upper carbon. After passing through 
the upper carbon across the arc and through the 
lower carbon it flows through a wire resistance to 
the other terminal of the lamp and thence to the 
line. This wire resistance is arranged so that it 
can be readily varied. 

Q. Explain the operation of the lamp. 

A. When the current passes through the coil 



270 QUESTIONS AND ANSWERS FOR 

it raises an iron armature or core to a certain 
height depending upon the strength of the cur- 
rent. Attached to this armature is a clutch de- 
vice which raises the upper carbon and ' l strikes ' ' 
the arc. The lamp burns gradually, consuming 
the carbons and lengthening the arc. As the arc 
lengthens its resistance increases and the current 
becomes less which allows the armature to drop 
down slightly. The clutch trips against a stop 
which lets the upper carbon rod slide through a 
little, thus shortening the arc until the current 
has increased enough to lift the clutch off from 
the tripping stop. The feeding of the lamp then 
ceases and the lamp continues to burn until the 
arc again becomes too long, when the operation is 
repeated. 

Q. What would you understand by a 2000 c. p. 
lamp? 

A. The meaning of this expression is indefi- 
nite. With open arc lamps I should understand 
a lamp which along the direction in which it 
gives the greatest amount of light (about 45 de- 
grees from the horizontal) produces an intensity 
of illumination equal to that of 2000 candles. 

Q. How much current passes through such a 
lamp, and what is the approximate pressure be- 
tween its terminals and the amount of power used 
in the lamp ? 



STEAM ENGINEERS AND ELECTRICIANS. 271 

A. The current is about 10 amperes; the pres- 
sure, about 45 volts (not including that which is 
lost in the wire resistance) ; and the power there- 
fore is about 450 watts. 

Q. What would you understand by a 2000 c. p. 
closed arc lamp ? 

A. One that uses about 450 watts power. 

Q. What current is used in a nominal 2000 
c. p. closed arc lamp ? 

A. When burning steadily, about 5 amperes. 
When the lamp first starts up it may be as high 
as 9 amperes. 

Q. What voltage exists across the arc of the 
closed arc lamp ? 

A. About 80 or 90 volts. 

Q. Why is a wire resistance placed in series 
with the arc for lamps used on constant pressure 
circuits ? 

A. For two reasons: First, a certain amount of 
resistance is necessary to steady the arc; second, 
the remainder of the resistance is used to cut 
down the pressure from 110 volts to about 50 
volts. 

Q. Could not two of these lamps be connected 
up in series across 110 volts circuit and so obviate 
wasting a large amount of energy in the wire 
resistance ? 

A. The construction of the lamps would have 



272 QUESTIONS AND ANSWERS FOR 

to be modified; an auxiliary fine wire coil con- 
nected across the arc is introduced and placed so 
that it controls the armature operating the clutch 
device. As the arc lengthens the pressure between 
the two carbons increases, and this sends more 
current around the fine wire coil which lowers the 
armature and causes the clutch to feed. 

Q. Are the closed arc lamps ever connected two 
in series ? 

A. Yes; across a voltage of 220 or more. 

Q. In connecting up arc lamps, does it make 
any difference which terminal of the lamp is con- 
nected to the positive side of the circuit ? 

A. Yes; the upper carbon must be connected 
to the positive side of the circuit, else the greater 
part of the light will be thrown uj^ward to the 
ceiling instead of downward, as it should be. 

Q. How can you tell whether the connection 
has been properly made ? 

A. While the lamp is burning look at the arc 
through a smoked glass; in the case of open arc 
lamps, the upper carbon should have a little crater 
at its lower end, while the lower carbon should burn 
slightly pointed. With closed arc lamps the differ- 
ence in appearance in the two carbons is very 
much less, though in either case the upper carbon 
will be the brighter. If a Weston voltmeter is at 
hand the polarity can be tested by means of it. 



STEAM ENGINEERS AND ELECTRICIANS. 273 

Q. What is the difference between a single-stroke 
bell and a vibrating bell ? 

A. A single-stroke bell is one which makes only- 
one stroke for each time that circuit is closed; a 
vibrating bell is one whose hammer continues to 
vibrate as long as the circuit is closed. A vibrat- 
ing bell may be changed into a single-stroke bell 
by short-circuiting the make and break mounted 
on the armature. 

Q. Suppose that you had several bells that you 
desired to have vibrate simultaneously from one 
push-button, how could you arrange them ? 

A. There are two ways: First, the bells could 
be connected in multiple; second, all but one of 
the bells could be changed to single stroke, that 
one being left vibrating ; then the whole number 
could be connected in series with each other and 
with the battery and push-button. 

Q. Show by diagram how you could connect 
three bells to ring by a single push-button. 

A. 




Q. Draw the connections for two bells to be 
rung by either of two push-buttons. 

18 



274 QUESTIONS AND ANSWERS FOR 



A. 



-tt- 



5~5 odioci 

Q. Draw the connections for a return call be- 
tween two points. 

A. 




Q. Draw the connections for an annunciator 
system. 
A. 




AMtomttfte 



Signal Bell. 



Q. What is an automatic set-back, and how is 
it arranged ? 

A. An automatic set-back is a device by which 



STEAM ENGINEERS AND ELECTRICIANS. 275 

an annunciator shows only the last call which has 
been made. This is accomplished by an auxil- 
iary electro-magnet placed in the annunciator so 
connected that current flows through it whenever 
any push-button is pressed. Attached to its arma- 
ture is the rod which resets the needles. 

Q. Draw the connections for a return call an- 
nunciator system. 

A. See " Roper's Handy-Book," page 762. 

Q. Should there be an automatic set-back on an 
elevator annunciator ? 

A. No. 

Q. How does a burglar-alarm system differ 
from an ordinary annunciator system ? 

A. The push-buttons that are placed in doors 
or window casings are of a different pattern, and 
moreover several are connected in multiple on 
one circuit. The annunciator has an additional 
bell in the auxiliary circuit, which circuit is 
closed if any one of the drops operate. This 
bell will therefore continue to ring until some one 
restores the drops to their normal position. The 
annunciator has several attachments not found on 
the ordinary annunciator, such as a switch to 
throw the instrument off in the daytime, a switch 
by which the condition of the batteries may be 
tested, and another which is thrown when it is 
desired to test the condition of any circuit with- 



276 QUESTIONS AND ANSWERS FOR 

out the noise of the bell. Sometimes a clock is 
added which automatically throws off the instru- 
ment at any desired hour. 

Q. What kind of battery cells are used with 
annunciator systems ? 

A. Cells of the so-called open-circuit type and 
usually some form of the zinc-carbon-sal-ammo- 
niac cells. 

Q. How many cells are necessary ? 

A. This depends entirely on the number of 
points on the instrument and upon the distance 
and size of wire. In houses, as a rule, four cells 
will be sufficient. If the distances are very long 
it will be necessary to increase the number of 
cells in series ; and if the number of points on the 
instrument is large, as, for example, in hotels, 
then it will be desirable to connect several of the 
cells in multiple with each other. 

Q. What principal systems of watchmen's clock 
are there ? 

A. The battery system and the magneto system. 

Q. Explain how a battery system is arranged 
and operated. 

A. The wiring of the system is similar to that 
of the simple annunciator system. The push- 
buttons are of such a shape that a circuit can be 
closed in them only by the insertion of a certain 
key that the watchman carries. The annunciator 



STEAM ENGINEERS AND ELECTRICIANS. 277 

of the ordinary system when slightly modified 
becomes the watchman's clock, the signal bell 
and automatic set-back being omitted. The ar- 
mature of each drop operates a needle which 
punctures a hole in the paper recording dial 
which is divided into spaces corresponding to the 
hours and fractions of an hour. This dial makes 
one complete turn in twelve hours, and therefore 
the position of the holes tells at what time the 
circuit was closed by the watchman. The dial 
also has a number of circles marked on it corres- 
ponding to the number of stations, and each 
needle pricks its holes in one of the circular 
spaces formed by these rings, so that a hole in a 
certain ring shows that the key has been put in 
the corresponding station push-button. 

Q. How does a magneto system differ from a 
battery system ? 

A. The wiring and clock are practically the 
same, but instead of a special push-button to be 
operated by a key a small magneto is placed at 
each station. The watchman carries a handle by 
which he turns the shaft of the magneto arma- 
ture. This sends a current through the corres- 
ponding coil at the clock and causes its needle to 
make a record. 

Q. What are the advantages of a magneto 
system over the battery system ? 



278 QUESTIONS AND ANSWERS FOR 

A. There are no batteries to renew and to take 
i3are of and the watchman cannot make a proper 
record on the dial without actually going to the 
station; whereas with the battery system, if the 
watchman can get at the two wires leading to any 
station to connect them together, he can make the 
dock register just as well as by going to the station. 

Q. What is a Lechanche cell ? 

A. A Lechanche cell has for one pole a zinc 
rod, for the other a carbon plate, and the two are 
immersed in a solution of sal-ammoniac. In addi- 
tion to this there is a block of compressed man- 
ganese binoxide. 

Q. What is the object of this manganese ? 

A. It prevents what is known as polarization of 
the cell. 

Q. What are the effects of polarization ? 

A. The voltage is diminished and the resistance 
increased by the accumulation on the carbon plate 
of particles of hydrogen gases. 

Q. What voltage does a single Lechanche cell 
produce ? 

A. About 1J- volts. 

Q. How could you obtain a voltage of 15 volts 
with Lechanche cells ? 

A. By connecting ten of them in series. 

Q. What are dry cells, and what are their ad- 
vantages and disadvantages ? 



STEAM ENGINEERS AND ELECTRICIANS. 279 

A. They are cells in which the solution has 
been reduced to a pasty condition. Their only 
advantage is their greater portability ; their dis- 
advantages are a high resistance and greater polar- 
ization. 

Q. Why and how is a zinc battery plate amal- 
gamated ? 

A. Zincs are amalgamated so as to prevent the 
consumption of the metal when the circuit of the 
battery is open. The process of amalgamation 
consists of dipping the zinc into weak sulphuric 
acid until it is clean, and then rubbing mercury 
on its surface with a cloth until it looks bright all 
over. 

Q. What is the best form of zinc pole, and why ? 

A. The best form is that which gives a cell of 
the least resistance, and this depends upon the 
form of the other pole. In order to diminish the 
resistance the plates should expose as much sur- 
face as is possible, and the distance between the 
plates should be as small as possible. Therefore, 
if the carbon pole is of cylindrical form the best 
shape for the zinc would be a hollow cylinder 
surrounding the carbon. 

Q. Which is the better for a carbon plate, one 
which is very dense and close in structure or one 
which is porous ? 

A. The porous carbon is much better, as the 



280 QUESTIONS AND ANSWERS FOR 

oxygen taken up in the pores assists in removing 
the hydrogen particles that collect on the carbon 
plate and produce polarization. 

Q. When cells of the zinc-carbon-sal-ammoniac 
type fail to operate properly, what would you 
do? 

A. I would examine first the zinc plate and see 
if it were eaten up, and if so, I would replace it 
with a new one. If the zinc is all right I would 
examine the solution, and if this is of a yellowish 
color a new solution is needed. If the cell has 
been in use some time it will be desirable to boil 
the carbon plate for some time in water. 

Q. Is the zinc-carbon-sal-ammoniac cell suitable 
for use in operating small motors or lamps ? 

A. No; the cell polarizes too readily; for such 
work the bichromate cell or the Edison-Lalande are 
adapted. 

Q. Describe the bichromate cell. 

A. The bichromate cell consists of a zinc and a 
carbon plate in a solution of chromic acid. As 
the zinc is attacked by chromic acid even when 
the circuit is open, the cell is arranged so that 
when not in use the zinc can be raised and held 
out of contact with the acid. 

Q. What is the pressure furnished by a bichro- 
mate cell? 

A. About 2 volts. 



STEAM ENGINEERS AND ELECTRICIANS. 281 

Q. Describe the Edison- Lalande cell. 

A. The Edison-Lalande cell consists of a zinc 
and a copper oxide plate suspended in a solution 
of caustic potash. 

Q. What is the pressure furnished by the Edi- 
son-Lalande cell ? 

A. About -j% volt. 

Q. Will a larger size cell give a higher voltage 
than a small cell ? 

A. No; the voltage is the same, but the resist- 
ance of the larger cell is less. 

Q. In mixing up a sal-ammoniac solution, is it 
better to use warm or cold water ? 

A. Warm water, because the sal-ammoniac when 
dissolving produces a considerable degree of cold, 
and this is liable to crack the glass jars. 

Q. Describe the Daniell cell, gravity pattern. 

A. The Daniell cell consists of a copper termi- 
nal made up of thin sheet copper, which is placed 
in the bottom of the glass jar; crystals of copper 
sulphate are strewn over the plate and water is 
added until the jar is nearly full. A zinc plate is 
suspended at the top of the jar and a little sul- 
phuric acid added to start the cell. 

Q. What is the voltage of the Daniell cell, and 
for what kind of work is it adapted ? 

A. The voltage is about one volt. The cell is 
adapted to work in which the circuit is closed 



282 QUESTIONS AND ANSWERS FOR 

practically all the time, as in telegraph work and 
in certain signal s} T stems. 

Q. What kind of cells are used for operating 
burglar-alarm and watchmen's clock systems, and 
how many? 

A. Some form of the zinc-carbon-sal-ammoniac 
cell. The number needed depends upon the dis- 
tances and the clock used, but generally about six 
will be sufficient. 

Q. When the wires of bell, burglar- alarm, or 
watchmen's clock system are installed in conduit, 
is there any limit to the number of wires that 
may be put in one tube ? 

A. As many wires may be put in one tube as 
can be readily drawn in and out. 

Q. What kinds of wire are used for this class 
of work? 

A. Generally a wire insulated with two layers 
of cotton dipped in paraffin, called annunciator 
wire, is used on account of its cheapness. Office 
wire, which is a heavier insulation of the same 
kind, is used generally for the battery or common 
wire. In better classes of work a rubber-covered 
wire is used for the common wire and a weather- 
proof or fire- and weather-proof insulation for the 
other wires. 

Q. What are the two principal telephone sys- 
tems ? 



STEAM ENGINEERS AND ELECTRICIANS. 283 

A. The exchange system and the intercommu- 
nicating system. 

Q. What is the difference between the arrange- 
ments of the two systems ? 

A. In the exchange system two wires run from 
a central point to each telephone subscriber. 
These wires are each connected to the drop or 
indicating device of the exchange switchboard. 
The exchange operator, by means of convenient 
plugs and cords, connects the circuit of any one 
subscriber to the circuit of the party with whom 
he desires to speak. In the intercommunicating 
system there are as many wires as there are 
instruments plus two or three common wires, and 
all of these wires run to each instrument termi- 
nating in a switch. By throwing this switch to 
the point corresponding to any desired party a 
subscriber puts himself in communication with 
that party. 

Q. How does a subscriber call up Central on the 
exchange system ? 

A. There are two methods of calling : one 
where a battery and vibrating bell is used, the 
other where a magneto bell is placed at each 
instrument. The battery call is suitable for short 
distances only, while the magneto is equally good 
for short and long distances. At the exchange 
there is a sort of an annunciator device in each 



284 QUESTIONS AND ANSWERS FOR 

circuit, so that when the subscriber presses his 
button or turns the crank of his instrument, as 
the case may be, a corresponding shutter falls on 
the exchange switchboard. 

Q. How are calls made by the exchange oper- 
ator? 

A. On the battery call system, the wiring and 
general arrangement being the same as for the 
return call annunciator system, the operator 
presses the button corresponding to the instru- 
ment of the subscriber desired. In the magneto- 
call system the operator has a magneto connected 
with a cord and plug. The plug is put into the drop 
corresponding to the subscriber desired, and the 
operator then turns her magneto handle which 
rings a magneto bell on the instrument. 

Q. What method of calling is generally used 
on intercommunicating systems ? 

A. The battery call. 

Q. For what kinds of work are the two systems 
adapted ? 

A. The intercommunicating system is adapted 
to installations of a few instruments where the 
distances are not great. Where the number of 
instruments is large the trouble from "cross-talk " 
becomes excessive, as does also the cost of wiring. 
In such cases it is advisable to use the exchange 
system. 



STEAM ENGINEERS AND ELECTRICIANS. 285 

Q. What is the general principle of the trans- 
mitter as now used ? 

A. The transmitter consists usually of a cup- 
shaped piece of carbon containing carbon gran- 
ules or particles against which lies a thin carbon 
diaphragm; the whole is contained in a hard- 
rubber case to which is attached the mouthpiece. 
Current from a battery is led into the diaphragm 
and passes through the contacts between the 
diaphragm and the carbon particles, through the 
contacts between the particles themselves and to 
the contact between the particles or containing 
carbon cup, and afterward returns to the other 
pole of the battery. When the mouthpiece is 
spoken into, the diaphragm is set into vibration, 
producing a varying pressure of the carbon con- 
tacts, which varying pressure produces a varying 
resistance, and therefore a varying current which 
is transmitted along the line to the receiver of the 
other instrument. 

Q. What is the general construction of the 
magneto receiver as now used ? 

A. The magneto receiver consists of the mag- 
net, either bar shaped or preferably of the horse- 
shoe pattern, on the pole or poles of which is 
mounted a coil of fine wire which is connected to 
the line. Close to this pole, but not quite touch- 
ing, is a thin, circular, soft, iron diaphragm; the 



286 QUESTIONS AND ANSWERS FOR 

whole arrangement is enclosed in a hard-rubber 
case. 

Q. What is the action of the receiver ? 

A. The varying currents produced by the 
transmitter flow along the line around the roils 
and produce a varying pull on the diaphragm, 
which sets the air into vibration affecting the 
ear. 

Q. What kind of wire is used for telephone 
installations ? 

A. For inside work on exchange systems a 
weather-proof or rubber insulated wire, twisted 
every two inches or so, is employed ; the size is 
about No. 18 or 20 B. & S. For single pairs of 
instruments or for intercommunicating work an- 
nunciator wire is used in the cheapest installa- 
tions, and for a better class of work office wire or 
fire- and weather-proof is used. 

Q. What kind of battery cells are used in tele- 
phone work ? 

A. Generally some form of the zinc-carbon-sal - 
ammoniac cell. 

Q. Is the battery on a closed circuit when talk- 
ing is not going on ? 

A. No; the battery is thrown off the circuit by 
an automatic hook which operates when the re- 
ceiver is lifted off the hook. 

Q. Mention some of the troubles which you 



STEAM ENGINEERS AND ELECTRICIANS. 287 

have met in the various parts of the telephone 
system. 

A. In transmitters : a packing of the carbon 
particles, breaking of the carbon diaphragm, bad 
connections from the battery to the transmitter, 
- and running down of the battery from various 
causes. In the receiver : a broken wire in the coil, 
broken wire between the coil of the receiver and 
the receiver terminals, and touching of the dia- 
phragm on the magneto pole. In the magneto : 
a grounding of the armature wire on the core or 
a broken wire on the armature, a bad connection 
between the armature and the terminals of the 
magneto. On the line : a ground, short circuit, 
or broken wire. 

QUESTIONS ON ELECTEICAL UNITS, PROPERTIES, 
AND MEASUREMENT. 

Q. "What are the three most important elec- 
trical properties ? 

A. Current, electro- motive force, and resistance. 

Q. What is another term for electro-motive 
force? 

A. Electrical pressure. 

Q. How may electrical pressure be produced ? 

A. The two most important methods are by 
means of chemical action and by the movement 
of a conductor near a magnet. 



288 QUESTIONS AND ANSWERS FOR 

Q. What is the unit of electrical pressure ? 

A. The "volt," 

Q. What is the instrument called that is used 
to measure electrical pressure ? 

A. The voltmeter. 

Q. Whenever there is a difference of electrical 
pressure between any two points, what will hap- 
pen if these two points are joined by a conductor ? 

A. An electrical current will flow from the high 
pressure point to the low so long as there con- 
tinues to be a difference of pressure between the 
two points. 

Q. Is there a mechanical pressure as well as 
an electrical pressure existing between the two 
points ? 

A. Yes; the substance which separates the two 
points is under an actual mechanical strain, the 
amount of strain increasing with the increase of 
electrical pressure. 

Q. How could you ascertain whether there was 
a difference of pressure between two points ? 

A. By connecting a voltmeter between the two 
points. If the needle of the voltmeter were de- 
flected, I should know that there was a difference 
of pressure between them. 

Q, What is used as a convenient standard of 
pressure ? 

A. A certain kind of cell called the Clark cell. 



STEAM ENGINEERS AND ELECTRICIANS. 289 

Q. What are some of the effects of an electric 
current ? 

A. It heats conductors carrying it, it exerts a 
magnetic force on all magnetic substances near the 
conductors, and it is able to decompose the solu- 
tions of many chemical substances. 

Q. What is the unit of current ? 

A. The ampere. 

Q. What is the practical definition of an 
ampere ? 

A. An ampere is the current which will deposit 
from a solution of silver nitrate .017 grain of 
silver in one second. 

Q. In the case of flowing water, what would be 
analogous to the ampere ? 

A. Since the ampere is the unit of rate of flow 
the corresponding unit for water would be a flow 
of one gallon per second. 

Q. Is the heating effect of an electric current 
proportional to the strength of current? 

A. It increases as the current increases, but 
very much faster ; for example, doubling the cur- 
rent makes the heating effect four times as great ; 
in fact, the heating effect is proportional to the 
square of the current. 

Q. What practical use is made of the heating 
effect? 

A. It is used in electric heaters and cooking 
19 



290 QUESTIONS AND ANSWERS FOR 

devices, and in heating the filaments of incandes- 
cent lamps. 

Q. Is there any danger in the heating effect ? 

A. There would be if the wires used for carry- 
ing currents were too small. In such a case the 
wires would become so heated as to be liable to 
set fire to woodwork in their vicinity. 

Q. What relation exists between the magnetic 
effect of the current and the number of amperes ? 

A. The magnetic effect is strictly proj)ortional 
to the number of amperes. 

Q. Is the ability of the current to decompose 
substances also proportional to the number of 
amperes ? 

A. Yes; strictly so. 

Q. What is the resistance of a conductor? 

A. The resistance of a conductor is the opposi- 
tion which that conductor offers to the passage of 
an electrical current. 

Q. What is the unit of resistance ? 

A. The ohm. 

Q. What is an ohm ? 

A. An ohm is the resistance of a column of 
mercury having a certain definite length (41.85 
inches) and a certain weight (223 grains) at 32° 
Fahr. 

Q. Are the standard ohms used in practice 
made of mercury ? 



STEAM ENGINEERS AND ELECTRICIANS. 291 

A. Xo; they are made of wire coiled up in a 
convenient form. 

Q. What effect has the length of the conductor 
upon its resistance ? 

A. The resistance is proportional to its length. 

Q. How does increasing the cross-section of a 
conductor affect its resistance ? 

A. It lessens it proportionately. 

Q. Suppose that a certain size of wire 1000 feet 
long has a resistance of two ohms, what will be 
the resistance of 500 feet of the same wire ? 

A. One ohm. 

Q. And suppose that the diameter of the 500 
feet of wire were made one-half its present value, 
what would the resistance be ? 

A. Since the diameter is halved, the new area 
will be one-quarter and the resistance will be four 
times as great, or four ohms. 

Q. What is the difference between resistance 
and conductivity ? 

A. Resistance is the opposite of conductivity. 

Q. When are two conductors said to be con- 
nected in series ? 

A. When they are placed like two horses driven 
tandem — that is, when one end of one conductor 
is joined to one end of the other. 

Q. What is the total resistance of two conduc- 
tors connected in series ? 



292 QUESTIONS AND ANSWERS FOR 

A. The total resistance is equal to the sum of 
the separate resistances. 

Q. When are conductors said to be connected 
with multiple or parallel ? 

A. When they are placed like two horses driven 
as a pair, the conductors being connected to each 
other as follows: 

If we may suprjose the conductors to be lying 
in the north and south direction, the north ends 
will be connected and the south ends will be con- 
nected together. 

Q. What is the rule for rinding the joint resist- 
ance of two conductors connected in multiple ? 

A. Divide the product of the two resistances by 
the sum. 

Q. When the resistances are equal, what will 
be the joint resistance ? 

A. One-half of the resistance of one of them. 

Q. What is specific resistance ? 

A. It is the resistance of a cubic inch of a sub- 
stance. 

Q. What are non-conductors ? 

A. Substances that have a high specific sub- 
stance; or, in other words, that offer a strong op- 
position to the passage of the current. 

Q. What are conductors ? 

A. Substances having a comparatively low spe- 
cific resistance. 






STEAM ENGINEERS AND ELECTRICIANS. 293 

Q. What is an insulator ? 

A. It is another name for a non-conductor. 

Q. What class of substances are good conduc- 
tors, and what class are insulators ? 

A. The metals are good conductors and the 
non-metals are insulators. 

Q. What are some of the best conductors ? 

A. Copper and silver. 

Q. What are some of the best insulators ? 

A. The best insulators are glass, porcelain, 
mica, rubber, and dry air. 

Q. What is Ohm's law? 

A. In an electric circuit the total current (in 
amperes) is equal to the total electric pressure (in 
volts) divided by the total resistance (in ohms). 

Q. What formula is used to express this law ? 

E 

A. C= —. Where C equals the current in 
R 

amperes, E equals pressure in volts, and R equals 
resistance in ohms. 

Q. Is this law applicable to circuits carrying an 
alternating current ? 

A. Not without modifications. 

Q. A certain electric circuit has a total resist- 
ance of 4 ohms, and there is an electrical pres- 
sure acting amounting to 8 volts, what will be the 
current ? 

A. Two amperes. 



294 QUESTIONS AND ANSWERS FOR 

Q. How great an electro-motive force will be 
needed to send a current of 10 amperes through a 
circuit having a resistance of 1 ohm ? 

A. Ten volts. 

Q. Suppose that we find in a circuit a current 
of 20 amperes, and with the pressure in the cir- 
cuit is 50 volts, what is the resistance of the cir- 
cuit ? 

A. f§, or 2 \ ohms. 

Q. Suppose that we have connected up in series 
three batteries, each giving an electro-motive force 
of 1.5 volts, what will be the pressure between the 
unconnected ends of the series ? 

1 3x 1.5, or4.5 volts. 

Q. Now, suppose that' connected in series with 
them is a wire having a resistance of 3 ohms, can 
you calculate what current will flow in the cir- 
cuit? 

A. Not unless I know the resistance of the 
batteries. 

Q. If the resistance of the batteries is -J- ohm 
each, what current will flow in this circuit ? Ex- 
plain how you will arrive at the result. 

A. Since each battery has a resistance of -J- ohm, 

the total resistance of the circuit will be ^ -f- \ -j- 

Jr -f 3, or 4J- ohms. By Ohm's law the current 

4| 
= — , or 1 ampere. 



STEAM ENGINEERS AND ELECTRICIANS. 295 

Q. Suppose that one of the three batteries was 
reversed so that it opposes the other two, what 
would be the net electro-motive force in circuit ? 

A. 3 — H, or l\ volts. 

Q. "When the electric pressure is furnished by 
the ordinary 110- volt generator, what will be the 
current flowing if one 16 c. p. lamp of 220 ohms 
resistance is turned on ? 

A. In this case the resistance of the generator 
is so small compared with the resistance of the 
circuit that it may be neglected in the calculation. 
The current will therefore be |^J, or J ampere. 

Q. What will be the current when two lamps 
are turned on ? 

A. By the rule for divided circuits the joint 

220 X 220 

resistance is — -, or 110 ohms. The cur- 

220 -f 220' 

rent will then be ^$, or 1 ampere. This is the 
total current flowing through the machine, one- 
half of it flowing through each lamp. 

Q. What would be the current when ten lamps 
are turned on? 

A. In this case, where the resistances of the 
separate branches are equal, the joint resistance is 
equal to the resistance of any one branch divided 
by the number of branches. The joint resistance 
is, therefore, -^°-, or 22 ohms. The current will 
be 1 ^, or 5 amperes. 



296 QUESTIONS AND ANSWERS FOR 

Q. What is a galvanometer, and how can one 
be made? 

A. A galvanometer is an instrument for detect- 
ing or measuring a current. It may consist of a 
fixed coil of wire and a movable magnet needle 
which is deflected by any current passing through 
a coil, or the coil may be small and movable and 
the magnet large and fixed. 

Q. What is the construction of the Weston 
instruments ? 

A. They consist of a fixed permanent magnet 
of horse-shoe form between the poles of which is 
pivoted a coil of fine wire. The indicating needle 
of the instrument is attached to the coil; the coil 
is held in the zero position by a bar of fine springs 
similar to the hair-spring of a watch. When the 
current passes through the coil, the coil is deflected 
against the action of these springs by an amount 
proportional to the current strength. 

Q. How would you connect a voltmeter so as 
to measure the voltage of a battery ? 

A. I would connect one terminal of the volt- 
meter to one terminal of the battery, and the 
other terminal of the voltmeter to the other termi- 
nal of the battery. 

Q. In the Weston instrument, does it make any 
difference which terminal is connected to the zinc 
pole of the battery ? 



STEAM ENGINEERS AND ELECTRICIANS. 297 

A. Yes; the terminal marked minus ( — ) should 
be connected to the zinc pole, otherwise the needle 
will tend to deflect in the wrong direction. 

Q. What is the most common range of a Wes- 
ton portable voltmeter? 

A. One reading from zero to 150 volts. 

Q. Could you measure accurately with such 
an instrument the pressure of a single battery 
cell ? 

A. No; the reading would be so small as to be 
inaccurate; it would be like trying to weigh a 
small boy on a set of hay scales. 

Q. Is there any way to measure accurately 
with such an instrument the pressure of a single 
cell? 

A. No; the instruments are, however, often 
made with a double scale and a double set of ter- 
minals, the lower scale reading from zero to 5 or 
from zero to 15 volts. 

Q. Suppose that with such an instrument you 
wish to measure a voltage which you knew to be 
in the vicinity of 220, how would you do it ? 

A. I would first connect across the circuit, 
whose pressure I desire to measure, two 110-volt 
lamps in series; then I would connect the volt- 
meter first so as to measure the pressure between 
the terminals of one of the lamps, and next be- 
tween the terminals of the other lamp. The sum 



298 QUESTIONS AND ANSWERS FOR 

of the two pressures would be the pressure of the 
circuit desired. 

Q. How would you connect the voltmeter so as 
to obtain the pressure between the terminals of 
the lamp ? 

A. I would connect a wire from one terminal 
of the lamp socket to one terminal of the volt- 
meter and another wire from the other terminal 
of the lamp socket to the other terminal of the 
voltmeter. 

Q. How does the Weston ammeter differ from 
the voltmeter in construction ? 

A. A strip of heavy metal connects across the 
terminals of the coil so that it takes the bulk of 
the current to be measured, only a very small 
fraction passing around the coil. 

Q. How would you connect an ammeter so as 
to measure the current passing through a certain 
number of incandescent lamps ? 

A. I would insert the ammeter in the branch 
circuit which supplies those lamps, opening the 
circuit at some convenient point and connecting 
one terminal of the opening to the proper termi- 
nal of the ammeter and the other side of the 
opening to the other terminal of the ammeter. 

Q. Suppose that when you had connected up 
the ammeter you found that the needle was de- 
flecting in the wrong direction ? 



STEAM ENGINEERS AND ELECTRICIANS. 299 

A. I should know that the connections needed 
to be reversed ; the plus terminal must be con- 
nected to the plus side of the circuit. 

Q. Suppose that you had a coil of copper wire 
and wished to know its resistance, how could you 
■ find it out ? 

A. If I had access to wire tables I would meas- 
ure first the gauge of the wire and would then 
either measure its length or weigh it, whichever 
were the easier. The ordinary wire tables give 
the resistance per 1000 feet of various gauges of 
wire and also the pounds per 1000 feet. 

Q. How could you measure the resistance ? 

A. If I had an ammeter and voltmeter of 
proper range I would put the ammeter in series 
with the wire and pass a current through it. I 
would then connect the voltmeter to the terminals 
of the wire. The reading of the voltmeter would 
give the number of volts and the reading of the 
ammeter would give the number of amperes pass- 
ing through the wire, and the quotient of the volts 
divided by the amperes is by Ohm's law the re- 
sistance in ohms. 

Q. How great a current would you send through 
the wire ? 

A. That would depend upon the size of wire 
and the range of the ammeter. I would send a 
current large enough to give the maximum read- 



300 QUESTIONS AND ANSWERS FOR 

ing of the ammeter unless this heated the wire; 
in this case I would cut the current down until it 
produced no appreciable rise of temperature in the 
wire. 

Q. Why would you not use a current great 
enough to heat the wire ? 

A. This would change the very thing which we 
want to measure — namely, the resistance. 

Q. Is there any way of measuring resistance 
without the use of both voltmeter and am- 
meter? 

A. Yes ; the resistance may be measured by 
means of the voltmeter alone, provided we know 
its resistance. 

Q. Explain how you would proceed to measure 
a resistance by the voltmeter alone. 

A. See " Roper's Catechism," page 289. 

Q. For what practical cases is this method 
largely used ? 

A. For measuring high resistances such as the 
insulation resistance of different parts of a dynamo 
from the frame and the insulation resistance of 
wiring circuits to earth. 

Q. Show by a diagram how you would connect 
to measure the insulation of the armature coils of 
a dynamo from the frame. 

A. See "Roper's Catechism," page 290. 

Q. How would you measure the power used in 



STEAM ENGINEERS AND ELECTRICIANS. 301 

any part of a direct current circuit, for instance, 
in a group of lamps ? 

A. I would connect an ammeter, so that the 
entire current which flows through the lamps also 
flows through the ammeter. I would connect a 
voltmeter across the branch circuit which supplies 
the lamps as near as possible to the lamps. I 
would read both instruments and multiply the 
readings together, thus obtaining the power in 
watts. 

Q. How can you obtain the horse-power ? 

A. By dividing the number of watts by 746. 



WHAT TO DO IN CASE OF 
ACCIDENTS. 

FIRST AID TO THE INJURED. 

Injuries caused by machinery are usually ac- 
companied by bleeding. This bleeding may come 
from the arteries, which are the channels through 
which the blood passes on its way from the heart 
to the various parts of the body. In this case it 
is of a bright scarlet color, and escapes in spurts 
like water from a hose attached to a pump. Or 
the bleeding may come from the veins, which are 
the channels through which the blood flows on 
its way back to the heart. In this case the blood 
will be dark in color and will flow out in a steady 
stream without spurting. A third form of bleed- 
ing, known as capillary bleeding, consists in a leak- 
ing of blood from the smallest blood-vessels. 

Capillary bleeding is easily stopped by folding 
up a piece of cloth or a handkerchief, placing it in 
the wound and tying it there. 

Bleeding from the vein can be stopped by rolling 

up a handkerchief into a ball, placing it over the 

vein below the wound and then tying a second 

handkerchief tightly around so as to make the 

302 



WHAT TO DO IX CASE OF ACCIDENTS. 303 

first handkerchief press hardly enough upon the 
vein to close the channel. 

Arterial bleeding is by far the most dangerous, 
and it must be quickly and completely stopped. 
This is done by means of a so-called Spanish 
windlass (Fig. I), which consists of a piece of 
-rope or cloth tied around the limb above the wound 
and then twisted up tightly by means of a stick. 
The arteries lie more deeply imbedded in the 
muscles than do the veins, and they cannot be 
completely compressed by the windlass unless a 
firm compress, made of a piece of wood, a small 
stone, or a rolled-up handkerchief, is laid over 
the artery. While one person is getting the wind- 
lass ready, the artery should be temporarily com- 
pressed by another person, who should grasp the 
limb with the fingers and put on as strong a pres- 
sure as possible with his thumbs. 

In Figure II, A shows the location of the artery 
behind the knee-joint. At B it divides into two 
branches. 

In Figure III, A indicates the location and the 
direction which the artery takes in the thigh. 

In Figure IV, A is the artery in upper arm ; C 
and B the two arteries on the inner and outer side 
of the forearm. 

The beating of the arteries can be recognized by 
feeling in their course, as indicated by the dia- 



304 WHAT TO DO IN CASE OF ACCIDENTS. 




WHAT TO DO IN CASE OF ACCIDENTS. 305 

gram, and the compresses should be applied in 
these localities (above the cut or wound). 

In addition to the above treatment, the applica- 
tion of ice or cold to the affected part is beneficial. 
Elevation of the injured limb also tends to check 
the bleeding. 

Never make a man sit or stand up, if he has 
lost much blood, for he is very apt to faint, which 
may cause death. 

It is always well to keep the head lower than 
any other part of the body, in order to prevent 
fainting and to decrease the work of the heart. 

BURNS. 

Burns may be divided, according to their ex- 
tent, into three classes. First, those in which the 
skin is merely reddened. Second, those in which 
blisters are formed. Third, those in which the 
skin is either partially or wholly destroyed by 
charring. 

The amount of danger depends entirely on the 
extent of surface affected, a complete destruction 
of one-third of the skin on the body usually 
proving fatal, while, if the skin is only reddened, 
two-thirds of the surface may be affected without 
death resulting. 

Treatment. — As the results of scalds are the 
same as those of burns, they should receive the 
20 



306 WHAT TO DO IN CASE OF ACCIDENTS. 

same treatment. The modern antiseptic methods 
require materials that are usually not at hand 
in an emergency case. The following steps may 
be taken previous to the arrival of the physician. 

If the size of the burn is not very great, it is 
sufficient to wrap the affected part in cloths soaked 
with a strong solution of common baking soda in 
water. If this is not available, soak the cloths in 
a mixture of equal parts of sweet oil and lime- 
water. 

If blisters have formed, prick them with a 
needle so as to let out the liquid, but be careful 
not to break or tear off the skin which covers the 
blister. Give a good drink of whiskey or two 
teaspoonfuls of aromatic spirits of ammonia. 

If the burn be large, in addition to the above 
treatment the patient should be at once put to 
bed and covered with blankets. Hot- water bottles 
should be applied to his body, so as to keep up 
the temperature and to prevent shock, which 
would probably result fatally. 



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